Short answer
The Santorini hot springs are in a small bay on Palea Kameni, the older of the two volcanic islets in the middle of the caldera. You can only reach them by boat: the boat stops near the entrance of the bay and you swim the last 50 metres or so. At the source the water is about 30–35°C, warmer than the sea around it, and iron turns it orange-brown. Wear a dark swimsuit and leave jewellery on board.
- Where
- Palea Kameni, in the caldera
- Water at the source
- About 30–35°C
- How to get there
- By boat, then a short swim
- Entry
- Free; you pay for the boat
The hot springs are the stop guests talk about most on our Santorini yacht cruises, after the sunset. You jump off the boat in the middle of the caldera, swim into a quiet bay between black lava rocks, and the water turns warm and orange around you. Both our semi-private catamaran cruises from Vlychada Marina stop here every day of the season, so this is what the swim is like, how warm the water really is and what to wear.
Where are the hot springs?
The springs are in a small bay on the east side of Palea Kameni, the older of the two volcanic islets in the middle of the caldera, between Santorini and Thirasia. The bay faces Nea Kameni, the larger islet with the crater walk.
There is no road, beach or jetty on Palea Kameni. The only way in is by boat, and most boat tours in Santorini include the stop. Day trips leave from the old port of Fira and from Athinios; our cruises come in from Vlychada Marina on the south coast.
How warm is the water?
Where the warm water rises, close to the rocks at the back of the bay, it is about 30–35°C all year. A few strokes further out it mixes with the sea, so most of the bay feels like a warm bath rather than a hot tub. How much warmer it feels depends on the sea around it:
| Month | Sea | Hot springs | How it feels |
|---|---|---|---|
| March | 16°C | 30–35°C | Biggest difference; a real warm pool |
| April | 16°C | 30–35°C | Warm patch stands out clearly |
| May | 19°C | 30–35°C | Noticeably warmer than the sea |
| June | 22°C | 30–35°C | Pleasantly warmer near the rocks |
| July | 23°C | 30–35°C | Warmer near the rocks only |
| August | 24°C | 30–35°C | Smallest difference of the year |
| September | 24°C | 30–35°C | Smallest difference; easy long swim |
| October | 22°C | 30–35°C | Warm again by contrast |
| November | 19°C | 30–35°C | The warm patch stands out again |
Sea temperatures are long-term monthly averages for the Santorini coast (source: weather2travel); the 30–35°C at the source is the range usually given for the springs. For the rest of the year month by month, see the best time to visit Santorini.
Why is the water orange?
The warm water rising from the volcano carries iron, manganese and sulphur. When the iron meets the oxygen in the sea it turns into fine rust-coloured particles, which is why the bay looks orange-brown against the blue water outside it. The colour is strongest close to the rocks, where the warm water comes up.
You may notice a light smell of sulphur, and some guests find their skin looks slightly yellow afterwards. Both go after a shower. People have long said the mineral water is good for the skin and the joints; we cannot point you to a medical study, so think of it as a warm, unusual swim rather than a treatment.
How the swim works
The boat stops near the entrance of the bay, and from there you swim in. It is about 50 metres, two to five minutes at an easy pace, and the water is too deep to stand until you reach the rocky edge. The crew tells you where to swim and how long the stop lasts before anyone gets in.
- Swim with a float if you are unsure. There are floats on board; take one even if you swim well, so you can rest in the warm water.
- Stay in the water. There is nowhere to sit or stand on the islet, and the rocks are sharp.
- Keep the boat in sight and come back when the crew calls.
- Children should be confident swimmers, with an adult next to them in the water.
On a private boat tour you decide how long to stay in the warm water.
On a windy day in July or August the sea at the entrance can be choppy. If it is not safe to swim, the captain will say so and the cruise goes on to the next stop.
What to wear and bring
- A dark swimsuit. The iron leaves orange marks on white and light fabric that do not always wash out.
- No jewellery. Sulphur can tarnish silver; leave rings and chains in your bag on board.
- An old towel or the boat’s towels for when you come out, and a change of swimwear if you want a clean one for lunch.
Everything else (towels, snorkel gear, drinks) is on board. For the rest of the packing list, see what to wear on a catamaran in Santorini.
How the hot springs formed
Palea Kameni and Nea Kameni are the newest land in Santorini. Both grew out of the sea inside the caldera from small eruptions: Palea Kameni about 2,000 years ago, Nea Kameni over the last few centuries, with the last eruption in 1950. The volcano is still active underneath, and seawater that seeps into the warm rock comes back up through cracks in the bay as the hot springs.
Are the hot springs worth it?
For most guests, yes, as long as you know what to expect. It is a natural warm patch in the sea, not a spa: no pools, no changing rooms, and the water is lukewarm rather than hot for most of the bay. What makes it worth the swim is the setting: warm orange water between black lava rocks, in the middle of the caldera, with the cliffs of Fira and Oia in the distance. It is at its best in spring and autumn, when the difference between the sea and the springs is biggest.
