The warm springs lie around Palea and Nea Kameni, two small isles that rose from the sea after the volcano's eruption of 1570. The water is dark and reddish, colored by sulfur, iron and manganese, and warm rather than hot. The springs are natural and sit in the bay of Agios Nikolaos.

A visit is a boat trip out of Fira bay. Once the boat anchors, you swim in the warm water for about 30 minutes, and many people smear on the mud. Bring an old swimsuit and a spare, because the sulfur smell clings. From Nea Kameni, walkers can climb toward the smoking crater.

• Wear an old swimsuit and bring a spare, since the sulfur smell is hard to wash out of swimwear.
• Light-colored swimsuits can be stained by the sulfur and iron in the water, so avoid them.
• The water is warm rather than hot, at about 30 to 35 degrees Celsius.
• Vents on Nea Kameni are seen from a safe distance; scientists monitor the underwater activity and the springs are safe to visit.