We booked this tour for our last full day in Greece. We were hoping it would be the highlight of our three week trip, but instead it was a huge disappointment, at best. We decided to use Caldera's Boats, even though we were staying in Oia, because the tour company in Oia never responded to my email. We were told that since the last stop on this tour was in Oia, we could disembark there and return to our hotel.
We took the taxi from Oia in the morning (15 euros), then the cable car to the port (10 euros). When we boarded the boat, we were herded on like cattle with dozens of other tourists. The first stop was the volcano, which was very interesting (we had educated ourselves beforehand) and quite picturesque. The supposedly guided tour of the volcano was really a hurried explanation of the area at a few stops along the way. We were rushed up and down the mountain so the boat could depart at its scheduled time (which it didn't).
The boat then lurched through very rough seas, due to the wind, and arrived at the next stop, the "hot springs", which, at 80 degrees, were not even as warm as our local swimming pool. Worse yet, if you wanted to go to the hot springs, you had to swim 60 meters through 68 degree water to get there. Even though I'm an experienced swimmer, I passed on the opportunity and am glad I did because those who went swimming came back on board shivering.
Next stop was the island of Thirassia. We were given the choice of staying in the run-down port or going to the town at the top of the hill, which required either climbing 450 steps or riding a donkey. As our legs were very tired after three weeks of walking/hiking all over Greece and we don't care to ride on animals, we chose to stay in the port, which consisted of three or four not so desirable restaurants and one little shop. We were rather surprised to find that, unlike what we were told when I called Caldera's Boats the day before, lunch was not included in the price of the tour. Fortunately, we found a place to eat that took credit cards as we were nearly out of cash. We then hung out for over an hour waiting for the boat to leave.
After Thirassia, we were supposed to be able to get off the boat in Oia, but due to rough seas, the boat didn't stop there and went back to Fira. We had to take the cable car back up the hill (another 10 euros) and taxi back to our hotel (20 euros).
Needless to say, we do not recommend Caldera's Boats in the slightest. We were given erroneous information ahead of time, the tour guide was inexperienced and very unprofessional, and other than the volcano, the trip was an entire waste of time. Furthermore, nobody on the staff seemed to care about all the problems...even though several people wanted to disembark in Oia, there was not as much as a "we're sorry for the inconvenience". Anything the tour guide said over the PA system was so garbled that we couldn't understand what was said. There was never any safety explanation or description of where to find life vests and such, even though the water was beyond rough and we felt even being on the boat was dangerous.
When we booked the tour, I was surprised at how little it cost. As they say, you get what you pay for. If you want a boat tour while on Santorini, pay the price to look elsewhere.