Sit back and relax as you take a boat tour from Thira Port to "the Volcano" in a glass-bottom boat.
The two small islands in the center of the Santorini caldera, Palea and Nea Kameni, "the Volcano" to the local people, are the youngest volcanic lands in the Eastern Mediterranean. Palea Kameni (Old Burnt Island) is less than 2,000 years old, while Nea Kameni (Young Burnt Island) began to form only 425 years ago, and its youngest lavas are less than 50 years old. These two islands represent the volcano's most recent activity--which can still be experienced today.
You can explore the volcano and other unique volcanic activity on a boat trip to Santorini's Volcano. With a 1.5-hour stop, there is enough time to walk to the crater and observe the smoke with traces of sulphur that is emitted from a number of spots. In other spots, you'll find that the ground and stones are too hot to touch. After leaving the volcano, some tours will take in the Hot Springs--thermal mud baths and an interesting place to go swimming. Most boat tours finish their tour at the village of Oia, just in time for the most spectacular sunset in the Cyclades.
Travellers are really spoiled for choice, as there are many different companies offering this type of tour. Some are more basic (Volcano only), while others take in all that I outlined above and more (the archaeological site of Akrotiri). The most reliable tour companies can be found on the main strip in Thira Town, and don't be afraid to shop around for the best deal--especailly in the shoulder seasons.