Nea Kameni and Palea Kameni — the "Burnt Islands" — are the volcano's newest work, pushed up over the last two thousand years on the floor of the crater that blew the middle out of Santorini. Every cruise we run makes this its swim stop. You are anchored inside an active volcano, in water hundreds of metres deep, with the caldera walls standing three hundred metres above you on every side. Nobody swims here for the first time without stopping to look up.
The warm springs — when the weather allows
Tucked into the little cove of Agios Nikolaos on Palea Kameni, volcanic vents warm the sea and stain it a startling rust-orange with dissolved iron. When we can reach it, you swim from the boat through progressively warmer water until you're floating in the volcano's own jacuzzi, with a tiny white chapel watching from the rocks.
We say when deliberately. The cove is open and shallow, and it takes wind and swell badly — on plenty of days the sea makes holding a boat there a poor idea, and we don't pretend otherwise. Treat the warm springs as the bonus they are: the volcano swim happens on every cruise, and the springs happen whenever the day is kind enough. Nobody has ever come back from the crater swim feeling short-changed.
Does the boat stop on the volcano itself?
No — and it's worth knowing before you book anything on the island. Our cruises sail close along Nea Kameni's black lava flows, near enough to smell the faint sulphur on a still day, but don't dock for the crater hike; that's a separate walking excursion on dedicated ferry boats, a hot, shadeless 30-minute climb we'd honestly rank below the swim. From a catamaran you get the geology, the story and the water — without the queue up a gravel path in beach sandals.
The dark swimsuit rule
The springs are mineral springs in the most literal sense: iron and sulphur compounds hang in the water, and they will leave a faint orange signature on light-coloured lycra that no hotel laundry fully undoes. Wear a dark swimsuit for this stop — it's the single most useful packing tip on this island, and the reason it's printed on our packing list in bold.
Photo tip
The colour gradient is the shot: shoot from the deck looking down as swimmers cross the line where blue sea turns rust. On the sunset cruise the low light turns that boundary almost metallic. In the water itself, keep the phone in a floating case — the volcano has collected several sacrifices.
The honest caveat
The warm patch is a cove, not a swimming pool: nearest the vents it's genuinely warm, at the edges just pleasantly less cold, and after rain the mineral cloudiness thickens. Also, the seafloor near the chapel is soft volcanic mud — some guests love wearing it (it's a spa thing, apparently), others prefer to float and abstain. Both are correct.
