Formed by a massive eruption 3,500 years ago, Santorini's caldera is one of the Med's greatest natural spectacles. On this morning cruise, you'll climb aboard a wooden sailboat and glide to Nea Kameni and Palea Kameni – the two volcanic islets that breach from the water – and continue along the edge of the caldera.
First up is Nea Kameni, the larger of the twin isles. Hike up to its crater, striding over solidified lava fields to see its steamy fumes. Take in the views over the its harsh, moon-like landscapes and Santorini in the distance. Next, you'll cruise to the thermal springs of Palea Kameni, where you'll get the chance to swim in the mineral-rich waters, which can reach temperatures of 35°C. There's also an eminently Instagrammable Orthodox chapel by the water's edge.
Then, it's back on the boat to cruise along the coast, where whitewashed houses perch high above the caldera's northern edges, before returning to the Athinios port.