The volcanic isles of the caldera are a must-see when in Santorini. On this full-day cruise, you'll climb aboard a wooden sailboat and glide to Nea Kameni, Palea Kameni and Thirassia – the three volcanic islets that breach from the water – and continue along the edge of the caldera.
First up is Nea Kameni. Hike up to its crater, striding over solidified lava fields to see its steamy fumes. Take in the views over the 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.
Head onshore to explore Thirassia and you can take a walk around its active crater, or spend some time in the hilltop village of Manolas – the views are knockout. Then, it's back on the boat to cruise along the coast, returning to Athinios port.