"Hi Tom, Thanks again for the super week on Santorini! It really was the experience I expected and I would heartily recommend your trip to anyone interested in combining a holiday on the Greek islands with geologically fascinating day walks. Well done!" (B. Davenport, Bremen)

Santorini's caldera cliffs

Church in Fira with the caldera and Nea Kameni volcano in the background

Location of Santorini in the Aegean Sea

Walking along the bizarre pumice cliffs on Thera's south coast

Red poppies on Santorini's fields in springtime

The huge pumice and ash deposits of the Minoan eruption (ca 1613 BC) of Santorini; two students for scale

Lunch break in a lonely bay at the caldera

Colorful and nested houses of Oia, Santorini

Group photo at Ag. Nikolaos on the volcanic island of Palea Kameni

Colorful volcanic tuff layers in the caldera walls telling the violent past of the island

Deep fracture at the top of the Mikri Kameni lava dome from 1570 on Nea Kameni Island

At the red beach of Santorini - the interior of an ancient cinder cone perfectly exposed

On a boat trip with Captain Sostis
This walking tour for a small group (6-12 participants) explores the fascinating natural and cultural history of the volcanic island of Santorini. The program is a series of excursions with focus on Santorini's outstanding, text-book quality volcanic and geologic features, as well as its natural beauty and cultural history.
- Exclusive program including private boat tours
- Intense enjoyment of nature
- Excellent Greek (Santorinian) cuisine
- Charming, quiet accomodation in superb location
- Good mixture of geology, relaxation and fun
- Competent volcanologist guide
8 days itinerary
Note:
The following program is indicative - depending on weather and other conditions, it could be modified on location.
Day 1: Arrival to Santorini - Introduction
Arrival to Santorini - group dinner - introduction
Day 2: Whole-day walk along the scenic southern peninsula
Whole-day hike: explore the oldest volcanic products (near Akrotiri), observe spectacular geologic features (pillow lavas, fossils, dramatic faults) extraordinary scenery, swimming breaks,
stunning views from the lighthouse.
See also:
photos from this excursion in April 2019.
Day 3: Walk along the caldera - remains of prehistoric settlements - deposits of the Minoan eruption
Hike (3-4 hours total) along the spectacular southern caldera, observation of the spectacular pumice deposits from the past explosions of the volcano, visit to an abandoned quarry with prehistoric settlement remains, pick-nick lunch & swim break. Optional hike (2-3 hours) back along the beach and through pumice canyons and fields (or transfer by minibus).
See also:
photos from this excursion in April 2019.
Day 4: The volcanic islands Nea + Palea Kameni
Whole-day boat trip to the volcano, visit of the active craters of
Nea Kameni, warm volcanic springs (bathing) and extended lunch break on
Palea Kameni.
See also:
photos from this excursion in May 2019.
Day 5: Archaeologic highlights - spectacular walk along the caldera to Oia town
Visit the excavated ruins of the Minoan town covered by volcanic ash, then visit the
capital Fira and its outstanding
archaeological museum. In the afternoon, we follow a
dramatic trail around the impressive northern caldera reaching the
picturesque town of Oia.
See also:
photos from this excursion in April 2019.
Day 6: Free day or optional excursion
The day is a spare day or otherwise at your free disposal. An optional half-day excursion can be offered.
Day 7: Prof. Ilias mountain - Ancient Thera - Perissa black sand beach
Whole-day hike: visit a Medieval village with its Venetian castle, climb Profitis Ilias Mountain (556m),
Ancient Greek town of Thera, descend to the black-sand beach of Perissa.
In the evening, we meet for a group dinner in a beach tavern.
See also:
photos from this excursion in May 2019.
Day 8: Departure
Departure or extension program.
Note:
If trips on small boat trips are for you, we recommend to add one day to the itinerary for tour with our small boat around the caldera. This results in the following 9-days itinerary:
9 days version
Day 1-7: Same as in 8-days itinerary
Same as in 8-days itinerary
Day 8: Boat tour around the caldera cliffs - visit Therasia Island
Half-day boat trip: visit the opposite island of Therasia, and sail closely around the steep caldera cliffs: an unforgettable experience!
Day 9: Departure
Departure or extension program.
Arrival info:
The tour starts and ends on Santorini. Participants usually arrange their own arrival to the island where we pick you up. On request, we can include your flight to Santorini or help finding the best connection/fare.
Tour type: Walking & study tour: geology & volcanism - nature & culture - archaeology
Difficulty: Moderate
Group size: 6-12
Duration: 8 / 9 days
Dates:
no scheduled dates at present
Price (per person): 1450 €
Included:
- 7(8) nights in double rooms incl. breakfast (buffet)
- 3x lunch (picnic style)
- Full dinner (incl. drinks in reasonable amounts) except on two days
- Water & house wine
- All necessary transfers on Santorini (incl. pick-up from and to airport/ ferry)
- Boat-trips as described in the program (depending on weather conditions)
- Entry fees to museums and archeological sites
- Accompanying material
- English-German-Greek speaking guide from our team
Tour guide
The tour is normally guided either by German volcanologist Dr. Tom Pfeiffer or photographer and amateur geologist Tobias Schorr. Both have been traveling on the Greek volcanic areas (Methana, Milos, Santorini, Nisyros) for more than 20 years and know the islands better than even most local people do.
Tom completed his PhD studies on the topic of the great Minoan eruption of Santorini. He made the important discovery of a 3600-year-old olive tree buried alive in the pumice deposit that now can be seen in the small geological museum in Perissa.
This allowed the most precise dating of one of the most significant natural event in the Bronze age (to 1613+-13 years BC) so far.
His colleague Tobias, with whom Tom alternates on this tour, is a true specialist for Greece in general, boasting in-depth knowledge about its culture, history, people, flora, fauna and of course geology. He is known for his good eye and discoveries of rare minerals, plants, animals, or hidden archeological artifacts during the various excursions.
8 days itinerary |
9 days version
8 days itinerary
Note:
The following program is indicative - depending on weather and other conditions, it could be modified on location.
Day 1: Arrival to Santorini - Introduction

One of our favourite tavern on the beach...

The ideal place for dinner at Acrotiri

Greek "Mezé"
Arrival to Santorini - group dinner - introduction
Day 2: Whole-day walk along the scenic southern peninsula

The Red beach from above - remnant of an old cinder cone

Deposits from glowing avalanches exposed on the coast

Sunset on a clear day
Today will be a whole-day walk at relaxed pace, following remote trails on the scenic southern peninsula. We observe the
oldest exposed volcanic rocks, a typical cross-section of a small volcano (cinder cone, crater with dike and lava-lake), marine fossils, dramatic faults and other
geologic highlights illustrating how this island was formed.
There will be an
excellent lunch in a small tavern on the way, and possibilities for swim breaks on beautiful beaches.
See also:
photos from this excursion in April 2019.
Day 3: Walk along the caldera - remains of prehistoric settlements - deposits of the Minoan eruption

The pumice quarry at Acrotiri

An prehistoric obsidian knife

Ignimbrite rocks (c) T. Schorr
Hike (3-4 hours total) along the spectacular southern caldera, observation of the spectacular pumice deposits from the past explosions of the volcano, visit to an abandoned quarry with prehistoric settlement remains, pick-nick lunch & swim break. Optional hike (2-3 hours) back along the beach and through pumice canyons and fields (or transfer by minibus).
See also:
photos from this excursion in April 2019.
Day 4: The volcanic islands Nea + Palea Kameni

On the crater rim of Nea Kameni volcano

Volcanic bomb on Nea Kameni

Sulphur crystals on Nea Kameni (c) Tobias Schorr
Whole-day boat trip (
private small boat from the beach below the hotel) to visit the historic volcanic islands of Palea and Nea Kameni (explosion craters, lava flows and bizarre lava domes, fumaroles, sulphur deposits,
bath in warm, iron-bearing springs). Short hike to the summit craters of the volcano. Extensive lunch and swimming break.
Evening lunch free.
See also:
photos from this excursion in May 2019.
Day 5: Archaeologic highlights - spectacular walk along the caldera to Oia town

One of the famous frescos found in Acrotiri, 1627 BC

Church Agios Minas in Fira

View onto the cliff of Fira
Short walk to and visit of the nearby Minoan excavations (if reopened by the time of the tour), coffee/ swim break on the beach of Akrotiri. Local bus transfer to the capital Fira, visit to the outstanding archeological museum, extended lunch break at free disposal (opportunity to buy souvenirs, send postcards etc.).
After lunch, we visit an excellent exposition of replica of the world-famous wall paintings of Akrotiri in the conference centre of Fira. We continue in afternoon to hike along the spectacular cliffs of the northern part of the caldera to the picturesque town of Oia. Visit to the remnants of a Venetian castle, eroded stratovolcanoes, tuff rings, ancient graves and observation of fossil stromatolites. Dinner in Oia, famous for its brilliant sunsets. Taxi or bus transfer back to Akrotiri.
See also:
photos from this excursion in April 2019.
Day 6: Free day or optional excursion

The upper part of Ia, Finikia (c) T. Schorr

A little chapel at Emporio (c) T. Schorr

A typical scene in Thira town (c) T. Schorr
This day is planned for the case that a tour could not be done due to weather conditions or other problems. This day can be used for exploring the island yourself. There is the bus stop in front of the hotel, so you can get easily to Thira and from there to all villages on the island. Also it is possible that Tom Pfeiffer offers an optional tour.
Day 7: Prof. Ilias mountain - Ancient Thera - Perissa black sand beach

The village center of Pirgos (c) T. Schorr

On the way from Profitis Ilias Mountain

Theater in Ancient Thera (c) T. Schorr
Whole-day walk to the Profitis Ilias Mountain, the highest peak of the island group (556m). From there we hike along an ancient trail to the impressive ruins of the ancient Greek town of Thera, excavated around 1900. On our way a coffee break in the medieval town of Pirgos with its Venetian castle, lunch snack under the shadow of trees next to the ancient Greek theatre. The excursion ends in Perissa with its famous black-sand beach on the early afternoon. The rest of day can be spent on the beach (with bus or taxi transfer back to the hotel arranged, or facultative hike back along the coast and through impressive pumice canyons).
See also:
photos from this excursion in May 2019.
Day 8: Departure

View to the caldera (c) T. Schorr

Thira from the airplane (c) T. Schorr

Evening view over Santorini (c) T. Schorr
Departure or extension program.
Note:
If trips on small boat trips are for you, we recommend to add one day to the itinerary for tour with our small boat around the caldera. This results in the following 9-days itinerary:
9 days version
Day 1-7: Same as in 8-days itinerary
Same as in 8-days itinerary
Day 8: Boat tour around the caldera cliffs - visit Therasia Island

Sailing on our small boat - great fun!

The chapel below Oia town (C) T. Schorr

Cliffs beneath Fira (c) T. Schorr
Half-day boat trip (private small boat) inside the caldera, likely to become an unforgettable highlight of the tour. After a lunch- and swimming stop on Thirasia island we sail slowly along Santorini's spectacular inner caldera cliffs and return to our hotel for a free afternoon (see photos taken during these trips). In the evening group dinner in a nearby beach tavern.
Day 9: Departure

View to the caldera (c) T. Schorr

Thira from the airplane (c) T. Schorr

Evening view over Santorini (c) T. Schorr
Departure or extension program.
8 days itinerary |
9 days version
Prices for tours at custom dates on request
Included:
- 7(8) nights in double rooms incl. breakfast (buffet)
- 3x lunch (picnic style)
- Full dinner (incl. drinks in reasonable amounts) except on two days
- Water & house wine
- All necessary transfers on Santorini (incl. pick-up from and to airport/ ferry)
- Boat-trips as described in the program (depending on weather conditions)
- Entry fees to museums and archeological sites
- Accompanying material
- English-German-Greek speaking guide from our team
Not included:
- Travel to and from Santorini
- Extra meals and drinks not mentioned as included in program
- Single room supplement
Discounts:
Returning customers receive 5% (or 8% - if you have been on at least 3 trips with us) discount on the base tour price.
Group booking discount: If at least 4 people together book this trip, 5% (additional) discount is given, combineable to a maximum of 10%.
Add-ons:
- Additional nights on Santorini: 85 EUR (double room) / 75 EUR (single room)
Additional info
Physical requirements
Some hiking experience needed, walking over loose ground, climbing and descending on smaller steep passages. Secure step, a good feeling for balance and no fear of altitude. Walking distances of up to around 12 km, climbing of up to 500 m, walking times up to 4-6 hrs during a full day. For details, see section in main text.
Arrival info
The tour starts and ends on Santorini. Participants usually arrange their own arrival to the island where we pick you up. On request, we can include your flight to Santorini or help finding the best connection/fare.
"Thanks for making our visit a great experience" (Larray & Linda from Oregon about the tour on Santorini)

Feedback from our guests

The small group, guided by Tobias Schorr

The cinder cone and red beach at Acrotiri.
Often, we receive very nice cards or other small signs of appreciation after a tour has ended. Here's an example from our recent tour tour on Santorini in May 2019. More photos of the tour you can find here Tour Photos.
"Dear tom,
Thanks a lot for great cooperation : travel agent called us to say guests had an outstanding tour with a wonderful guide J
All the best."
Olivier Jeannier
Agent de voyages Sales & Operations Specialtours & Groups
Tourisme Pour Tous
Myriam from France about our recent tour on Santorini

Les ponces de l'éruption Minoenne

Chèvre sur Palea Kameni

Le groupe avec des amis
"Bonjour de France, enfin du soleil ici pas le même que celui de Santorin bien sûr, mais c'est toujours agréable.
Le retour en France a été difficile après avoir vécu une semaine hors du commun dans un décor extraordinaire. Je remercie Tobias et toi pour votre façon de partager votre passion et de nous faire entrer dans cet univers décalé avec la vie "normale" de tous les jours.
J'ai apprécié la découverte géologique de l'île, l'initiation à la compréhension de la formation de l'île et des volcans, les rencontres avec des gens simples mais de caractère de Santorin.
Le temps s'est arrêté pendant une semaine et je garde des souvenirs d'odeurs, de couleurs, de plats partagés avec le groupe.j'ai revu les photos prises pendant le voyage, les couleurs et les paysages étaient tellement extraordinaires que les résultats sont surprenants même avec mon simple appareil photo. J'aimerais envoyer les photos de groupe prises dans la taverne de nicolas à "yurgos", peux-tu m'envoyer leur adresse?Egalement j'aimerais commander le livre de Walter Friedrich, mais je n'ai pas noté l'éditeur.Merci pour ces renseignements.
Bonne continuation dans tes voyages
ps: quelques photos jointes... Myriam" (Myriam T., Orléans)
Margrit from Potsdam about the Faszination Volcano tour on Santorini (Oct 09)
"Hallo Tom,
wieder einmal war es sehr schön auf Santorin und ich möchte mich für alles bedanken. Die Organisation, unser Hotel und die vielen neuen Eindrücke, welche du uns vermittelt hast sind kaum in Worte zu fassen. Vor allem aber danke, dass ich noch so kurzfristig teilnehmen konnte.
Eure Touren sind schon etwas Besonderes und mit viel Esprit, sehr persönlichen Einsatz, so dass man sich sofort wohlfühlt und immer gern wiederkommt.
Herzliche Grüße, Margrit" (Margrit from Potsdam, Faszination Volcano tour)
Gudrun from Dresden about the "Fascination Volcano" Tour in October 2009
"Hallo Tom,
nochmals vielen herzlichen Dank an Dich und die anderen für die schöne gemeinsame Woche mit dem gelungenen Mix aus Natur und Kultur, Sonne, buntem Stein und blauem Meer, Wandern und Neues Lernen, ein bisschen Anstrengung und Genuss!
... Weiterhin viel Glück bei allen Euren Unternehmungen und herzliche Grüße - Gudrun"
Sandra from California about the "Fascination Volcano" tour on Santorini:
"...Somehow I missed Tobias'link to photos and, fortunately, saw it through your note. Just finished looking at each image. Now, I"m exhausted! Stunning, and brings back keen memories, indeed. A whirling, dizzying journey to a version of Santorini unknown to most travelers. From moment we dropped luggage at Aktori to wine-tasting, to walk between villages, to our magical boat trips, to trek around caldera ledge, to climb up limestone mt., to smoking sulpher, to ancient city of Thira, to dreamy soups, best goat cheese, limpets and baklava...on and on. Tom and Tobias, our intrepid, ever-onward guides are a terrific team. Such compatibility among group of 17--wondrous again. How lucky was that??
Crazily, I just returned from 12 days in China...thus, a combo Greece/China 5-week adventure to savor and treasure. From yogurt, white villages & volcanoes to noodles, mountain temples & cave grottos. All intrigue and mystery and contrasts galore...
Best hugs,
Sandie"
Valerie's feedback from the trip on Santorini, May 2009
"Dear Tom & Tobias. Thank you for our remarkable trek in Santorini and Methana--for the beautiful memories and breathtaking photos.
... Coming home to Tobias'pictures gave me time to slow down and appreciate the remarkable experience we had.
I braved edges with Tom's help, jumped on boats with swirling seas (Daphne said I landed, elephant like, on poor Steve flattening him). ... The views took my breath away. ... Remember the oasis where we drank fresh squeezed orange juice and cake? I doubt whether juice will ever taste that good again. ... Little did I know that a bonus to our trip was the leader's desire for good food--and wine-- at the end of the day.
I have new appreciation for magma, volcanic bombs, the beauty of the caldera, smoking sulphur, adjectives that describe volcanic formations and olive trees found preserved in volcanic ash.
Thank you Tom and Tobias for a remarkable experience, and for your good choice in participants. It was a great group. Valerie" (Fascination Volcano, Santorini tour)
"... This was one of those wonderful adventures that we loved at the time, but loved even more as we looked back at all of the places we'd been, the lovely people we met, the great bond we developed. And......a birthday - high atop a volcano - that I will remember forever!
...Many hugs, Daphne" (D. Lewis, Washington, Santorini tour)
"Hi Tom,
This trip had everything! It was so much better than the standard tourist trip to Santorini (we felt so superior the folks who arrived on the 10 story floating skyscrapers and who apparently devoted their time on the island to shopping!). The hikes were good exercise, but with your encouragement to the less athletic among us, not too tough. We got to see so many parts of the island that most visitors don't get to see. And our reward for energetic hiking was delicious food, and lots of it. I appreciated that we got to eat a whole variety of local foods and wines which do not appear on the conventional menus of Greek restaurants in the U.S. I ate like a champ but didn't gain any weight!
I particularly appreciated the interpretation of the geology that you provided. On the way to the airport, you asked what was my favorite thing we did. I liked all the hikes, and especially the accomplishment of doing so much in a short time, but the big thrill, I think, was visiting the small geology museum in Perissa and seeing the critically significant preserved olive tree that you discovered and having you tell us about the find. Thanks for a really wonderful experience!" (Linda K, Olympia (WS), Santorini May 09)
"Hallo, Tom Zuerst vielen Dank für die tollen Photos, ich zeigte sie auch Helene und wir schwelgten wieder in Erinnerungen an unsere gemeinsamen Ferien. Es war eine wirkliche lehrreiche und zur gleichen Zeit auch sportliche Reise gewesen. Vor allem wurden auch unsere grauen Zellen aktiviert........
Auch über die Organisation muss ich Dir noch nachträglich ein grosses Lob aussprechen!!!!!
Irgendwann werde ich wieder eine Reise mit Deiner Organisation durchführen. Ich habe ja Einiges lesen können ( sites internet). Ich wünsche Dir eine schöne Adventszeit sowie natürlich auch vielleicht ruhige Weihnachten und einen tollen Rutsch ins Jahr 2009, sowie weiterhin viel Erfolg auf Deinen Reisen.
Und vielleicht irgendwann einmal wieder ?! Alles Liebe und Gute Uta" (
Fasination Vulkan, Santorin - Okt. 08)

"Tom, I'm thinking you might be on your way to Krakatau now -- I hope you all have a great trip. We had such an excellent time on our Santorini tour and I keep going back to your web site to figure out which volcano tour I want to try next... " (Jill, USA)
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Thanks again, Tom, for
this great week in Santorini.
Thanks for your competency, your kindness, your support in all situation. Thanks for the ouzo, the orange juice, the wine ...Keep in touch, Marie-Paule (
Fascination Volcano, Santorini)

 One of the participants sent us this nice spostcard she made herself.  Sacred Sites in Greece 2007 tour - hand-made postcard. |
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"Bonsoir Tom,
Merci pour les photos de Santorin qui sont magnifiques! Et encore
félicitations pour l'organisation de ce voyage. Quand on revoit les photos et le film qu'a fait Yvon, on se rend compte qu'on a non seulement
bien vu l'aspect Géologie de cette île, mais aussi l'aspect humain... Bonne continuation (les Suisses disent "bonne suite")
und alles gute. Nathalie et Yvon" (
Santorini tour, Sep. 2006)
"Un
très grand merci, Tom. Quel plaisir de revivre ces moments fabuleux grâce à tes photos ! J'espère que ton périple italo-sicilien se déroule aussi bien que le nôtre et je te redis ma reconnaissance pour la
qualité de l'organisation et les commentaires dont tu nous a fait bénéficier. Cordialement, Geneviève" (
Santorini tour, Sep. 2006)


Pirgos village on (Greek Easter) Good Friday (21 April 2006)
"Hi Tom, Now that we are back home, I wanted to thank you for your patience in showing us so many different aspects of Santorini: the history of volcanic eruptions and geology, local wine and food, Easter pageants, great walks and views, ancient excavations, etc. We enjoyed our stay very much! ... please give our regards to Koula and her family. We really appreciated that they invited us to share their fabulous Easter meal with them. It was very kind of Tobias to meet us for an evening on such short notice. ... Viele herzliche Gruesse Ursula and Bill" (May 2006, Ursula & Bill from Canada)

"Hi Tom, just a note to thank you for a great tour in October, it was great fun and I learned much, the food and company were excellent, the whole experience was fantastic. I see I even made it to the picture gallery! I have been busy with the thin sections, and have attached a few photos for you to look at. As is often the case ones that you expect to be good are disappointing, e.g. Cape Riva Ignimbrite, while Dacite, which looks to be just glass, shows a lot of structure, flow aligned crystals and good zoned feldspar and pyroxene. The sale of slides seems to be going well and I have stared a 'shop'on ebay http://stores.ebay.co.uk/Geosec-Slides which is difficult to keep stocked as they sell so quickly. The fund for future collecting expeditions is growing nicely! ... Once again thanks for October, send my regards to your Mother, and have a happy Christmas. Rob" (UK, Dec. 2005)
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Some nice words from a mixed group on Santorini ... (French, English, German speaking)

"Thank you Tom for a wonderful week of discovery & wonderful surprises! Judith."


Lunch break on the volcano of Santorini (1)

Lunch break on the volcano of Santorini (2)
"Dear Tom
Many thanks for a wonderful trip to Santorini, it was great!Hope things go well at the conference. Well, I said I would send you the octopus photos so here they are, hope they don't clog your mailbox I have no zip function on this computer!
All the best
Ann" (Newcastle, UK)

"Hi Tom, Thanks again for the super week on Santorini! It really was the experience I expected and I would heartily recommend your trip to anyone interested in combining a holiday on the Greek islands with geologically fascinating day walks. Well done!" (Bob Davenport, Germany)
"…I am so pleased to tell you about Tom's Santorini tours! My preference for travel is to be "as close to the ground" as possible. By that I mean I avoid tourist areas and really look for unusual or cultural/educational experiences.
Tom's tours are both intimate and professional. Tom is an expert in not only volcanic activity past and present, but he is also an expert on Greek life and culture. He knows the people, and they love him. Because Tom has lived in Greece for several months of the year for several years, he is well known and appreciated by the locals. This appreciation for Tom and the people he brings on his tours is rewarded by the community with absolute joy in service. For example, the last night of the tour we had a meal at a taverna on a beach. The restaurant gave us each a choice of anything on the menu. We were treated to amazing traditional Greek food, from small fish to hardbread, feta and olives, and amazing desserts. All of this was served in casual fashion on a makeshift outdoor patio almost in the sea! (not quite)
My favourite day was the trip to the volcano. We boarded a small boat and were transported to the volcano by the most humerous and typically Greek character, Sostas. Sostas is a friend of Tom's and can be seen on the Discovery show featuring Tom and Sostas and this tour. We landed on the volcano and Tom explained its history and answered any questions we had. We then swam in the volcanic waters at Sostas's house as Sostas prepared a traditional fish soup, hardbread, feta made from the goats that wander around the hills surrounding Sosta's property, olives, ect. An absolutely marvelous day. I must point out local tours to the volcano generally involve large boats with hoards of tourists who are dropped off and picked up with no explanation of the volcanic activity or history. Tom ensures a personal and educational cultural experience." (Shelly Logan, Canada)

"Hello Tom, I send our last Bulletin because there is one article on the excursion Santorini. I profit to thank you again very much for the way you lead this tour all the people were very happy." (Pierre Vetsch, Société Vulcanologique de Genève, SVG) - the report (in French) is found in the Bulletin Nr. 45 of the SVG.
Extract of the bulletin report mentioned above, referring to the Oct. 2004 tour: "...L'histoire de Calliste (le très beau nom donné à cette île par les anciens Grecs) est extraordinairement bien inscrite sur les flancs de sa caldeira (plutôt des restes de ses caldeiras successives). Des évidences ont été trouvées pour au moins 4 caldeiras, suite à autant d'éruptions explosives. La dernière, la Minoenne, date de 1645 BC. Elle est gravée dans la mémoire de l'humanité... tellement elle est récente ! C'est tout cela, et bien d'autres choses encore, que nous sommes allés admirer (et tenté de comprendre) au cours de ce voyage.
Le magicien dans cette affaire, c'est Tom Pfeiffer, géologue-volcanologue mandaté par notre président pour nous accompagner. Tom a parfaitement répondu à notre attente. Passionné, attentif, pédagogue, à l'humour taquin, volontiers francophone, il nous a fait découvrir les secrets de cette île en sept jours bien remplis. Je parlerai plus loin de son parcours professionnel..." (Jean-Maurice Seigne, Genève, Switzerland)