Santorini Hot Springs: the swim at Palea Kameni, and how to do it right

A bay of warm, rusty water on Palea Kameni

Palea Kameni is the older of the two Kameni islands in the middle of the caldera. The name means burnt island in Greek, which tells you what the first sailors thought of it. In a bay on its western side, warm underwater springs push water up through the sea floor. That water is rich in iron and other minerals, which is why it looks orange and rust-coloured where it mixes with the cooler sea around it. The mixing creates a visible boundary: you swim a few strokes from cool blue water into a warm brown-orange cloud. Boats cannot enter the shallowest part, so they anchor offshore and everyone swims the last stretch.

There is no pier, no ladder and no lifeguard. You slide off the boat's swimming platform or ladder and swim in. Because the warm water comes up in patches, you feel the temperature change in layers as you move. It is a swim of twenty or thirty minutes, not a soak for the afternoon. There is no beach to stand on, so everything you take in the water stays on you or on the boat.

The water temperature is a common question and the honest answer is that no official figure is published. Swimmers describe it as pleasantly warm near the springs and ordinary sea temperature elsewhere in the bay, and the sea itself varies hugely by season, from around 17 °C in winter to nearly 26 °C at the end of summer.

Why the islands are there at all

The Kameni islands are the visible top of the volcano that fills the caldera basin. The caldera itself formed when the Minoan eruption, around 1600 BC, blew the centre out of the older island and the sea flooded the collapse basin. That eruption buried the town you can now visit at Akrotiri Santorini, and it was one of the largest volcanic events in human history.

The islets grew back afterwards, built by eruptions spread over more than two thousand years. Written records and lava flows mark several major episodes: 1707 to 1712, 1866 to 1870, 1925 to 1928 and 1939 to 1941. The last small eruption was in 1950, when a lava dome formed on Nea Kameni, the younger islet about 2 km across that sits next to Palea Kameni. So when you swim in warm water at Palea Kameni, you are floating above the same system that built the crater you can hike on the neighbour island.

Is the volcano dangerous to swim near? The 2025 earthquake swarm, with more than 12,800 tremors and a state of emergency on the island, did not produce an eruption, and the caldera system is monitored. The warm springs themselves have been a tourist stop for well over a century. For wider context on safety and the volcano, see is Santorini safe.

What the swim feels like, honestly

Manage expectations and the visit rewards you. This is not Iceland's Blue Lagoon. The water near the springs is warm but not hot, tinted orange by iron, and the bottom is rocky in places. Light-coloured swimsuits come out stained, and some of that staining does not wash out. Smell of sulphur, faint but real, clings to skin until you shower. The swim from the anchored boat to the warmest patch takes a few minutes of open-water swimming, so basic confidence in the sea matters.

What you get in exchange is a swim in the caldera of an active volcano, surrounded by 300-metre cliffs, with lava rock under you and warm water around you. On a crowded day the warm patch holds dozens of swimmers from several boats, which some people find fun and others find busy. Go early or late in the day and you may share it with two other boats.

Practical line: bring a dark swimsuit, a towel the boat provides on the better cruises, and nothing you would mind losing in the water. Waterproof bags and phone cases help if you want photos while swimming.

By cruise boat from Fira Old Port

Fira Old Port, also called Gialos, is the classic departure point for the short volcano and springs trips. Getting down to it is part of the experience: ride the Santorini cable car down in about three minutes for $11.19 (€10), take the several hundred steps of the Karavolades path on foot, or join a mule train. Cable cars run every 20 minutes in summer and start early, which suits morning departures.

From the Old Port, the traditional boats cross the caldera in roughly 20 to 30 minutes to the Kameni islands, our estimate on the crossing time. The classic itinerary lands you on Nea Kameni for the crater walk, then anchors off Palea Kameni for the springs swim on the way back. Trips like the volcano and hot springs cruise follow exactly this pattern, with the €5 volcano park fee collected on the island. The same pattern runs from Athinios port, where the port cruise to volcano, hot springs and Thirassia departs with a pick-up option.

If you arrive on a cruise ship, your tenders dock at the same Old Port, so the short trips are the easiest add-on. See Santorini cruise port for how tender days work.

By catamaran from Vlychada, Oia or Ammoudi

The catamarans treat the springs as one stop on a longer coastal day. The southern fleet leaves Vlychada marina, sails north past red beach Santorini, White Beach and the Akrotiri lighthouse, then rounds into the caldera for the springs swim before lunch on board. Because the land path to Red Beach is closed by the municipality for rockfall, seeing it from the water is one of the few ways left to see it properly, and the catamaran route combines both in an afternoon.

From the north, boats leave Oia and Ammoudi bay, often at sunset, and work south to the springs and Thirassia. These trips cost more, from around $84 to $172 depending on food and group size, but they include meals, open bars and hotel transfers. Our pick for most visitors is this style: the premium small-group catamaran cruise covers the south coast, the springs and a proper meal in five hours with pick-up, which removes every logistics decision from your day.

How do you get to the departure points on land? Buses run from Fira Santorini across the island, with Fira to Perissa at $3.02 (€2.70) and most other routes at $2.46 (€2.20). Driving yourself gives the most freedom for early departures, see getting around Santorini.

Can you visit without a tour?

Only if you have your own boat or charter one. There is no public ferry to Palea Kameni and swimming from the caldera rim is impossible, the cliffs drop hundreds of metres. A self-drive rental motorboat from Vlychada is one option for confident boaters, though the springs lie across the caldera and the return against the afternoon wind is not beginner territory. Kayak tours paddle the south coast but do not typically cross to the springs, so check the route before booking a paddle as your springs fix.

For almost everyone, a scheduled boat is the answer, and that is fine. The choice is not tour versus no tour, it is a cheap big-boat trip focused on the volcano against a pricier catamaran where the springs are one of several stops. Both deliver the same swim in the same water.

When boats run, and when the bay is quiet

Boat schedules follow the tourist season rather than any official opening hours. In high summer, departures run from morning through to sunset trips, with the midday slots busiest because cruise passengers and hotel guests converge on them. The water is warmest in the afternoon of course, but so is the crowd.

The quiet windows, in our estimate, are the first departures of the morning and the sunset slots. Morning trips reach the springs before the midday fleet arrives, and the sea is usually calmest early, before the wind builds. Sunset trips share the bay with fewer boats because most swimmers are eating by then, and swimming in warm water while the light drops over the caldera edge is the best version of this experience. If your priority is photos without a crowd of heads in the frame, either end of the day wins.

Midday does have one argument in its favour: the air is hot, the springs are a genuine cooldown, and the sun lights the orange water at its most vivid. Choose midday only if your day is already shaped around a morning Fira to Oia hike or a beach morning.

The wind is the real gatekeeper

The July and August meltemi is the reason boat trips get cancelled. Operators list weather clauses on their bookings, and when the meltemi blows hard, small boats stop crossing and even catamarans reroute to lee sides. This is not a minor footnote, it is the most common reason a planned springs swim fails in high summer. Book your boat for early in your holiday, not your last day, so you have a fallback slot if a trip is cancelled. Free cancellation up to 24 hours ahead is standard on the listings we carry, which also lets you shift a booking to dodge a windy forecast.

Spring and autumn are calmer on average and the sea is still swimmable. Sea temperature sits around 19 to 20 °C by May, above 24 °C in July and August, and still around 23 °C through October, which is why shoulder season is a sweet spot: warm water, thinner crowds, lower prices on the boats. For month-by-month context see Santorini weather and best time to visit Santorini.

How long to give the whole outing

The swim itself is 20 to 40 minutes. The outing around it depends on the boat. A short volcano and springs trip runs three to six hours door to door including transfers. A catamaran day is five to six hours. Add transfer time to Vlychada or Ammoudi if you are not picked up at your hotel.

Our routing for a half-day plan: morning in Fira or your hotel, boat from late morning, springs swim, lunch on board or back on land, and the afternoon free for the museum of prehistoric Thera or a rest before the evening. If you land on Nea Kameni, budget the extra 1.5 hours for the crater trail and the $5.59 (€5) park fee. Wear shoes you can walk lava rock in, bring sun protection, and remember the caldera has no shade at all on the water.

Routing one: the cheap and classic half day

This is the route most first-time visitors take and it works. Morning cable car down to Fira Old Port, a traditional boat to Nea Kameni for the crater walk, the springs swim on the return, back by mid-afternoon. Total cost stays under $40 for the boat plus $11.19 (€10) cable car plus the $5.59 (€5) volcano fee. Boats like the volcanic islands cruise and the port cruise with Thirassia fill this shape, and both score above 4.3 across thousands of reviews.

The trade-offs: these are bigger boats with more people at each stop, no food beyond what you bring, and the springs swim is short. It is the right pick if the volcano crater is the headline and the springs are the bonus, or if you are watching costs. Pair it with a cheap evening in Fira afterwards and the day totals less than one catamaran ticket.

Routing two: the catamaran day with everything included

Five hours on a catamaran from Vlychada delivers the south coast, Red and White beaches from the water, a snorkel stop, the springs swim, and a BBQ with drinks on board, with hotel transfer both ways. Prices run from $84 to $148.73 depending on group size and menu. The crowd size is the real difference: boats cap at 18 to 22 guests against dozens on the big traditional boats.

Our pick here is the half-day exclusive catamaran cruise at $123.56, because 18 guests, an open bar and the Thirassia swim make the extra cost over the classic trips easy to justify for a couples or friends trip. For families with teenagers, the classic catamaran with BBQ at $91.52 keeps the same route and drops the price, with soft drinks included. Check the cancellation window when you book, 24 hours ahead for a full refund is the standard.

Routing three: sunset from the north

The third shape trades a daytime swim for the evening version. Boats leave Oia and Ammoudi bay in the late afternoon, cross to the springs or Thirassia, and end with the Santorini sunset happening from the water, the caldera cliffs glowing on one side and the village on the other. The catamaran cruise with swim-stops and sunset is the flagship of this shape, with a Greek meal on board.

This routing suits a shorter stay, because it consumes only an evening rather than a full day, and it pairs naturally with a day spent on the Santorini beaches or at the wineries. It costs the most, so our advice is to book it as your one big splurge rather than stacking it alongside another boat day. If you are in Oia anyway for the sunset crowds on land, being on the water is arguably the better vantage.

The eruption that made the caldera

Around 1600 BC the Minoan eruption threw an estimated 28 to 41 cubic km of dense rock equivalent into the sky, a VEI 7 event, one of the largest volcanic events in human history. It destroyed the flourishing town at Akrotiri, whose residents appear to have evacuated in time, since excavators have found no unburied human remains there and only a single gold object. The centre of the island collapsed and the sea flooded in, creating the caldera basin that boats cross today.

That event matters for the springs in a direct way: the caldera flooding concentrated the volcanic system underwater and offshore, and the resurgent volcanic activity afterwards built the Kameni islets inside the drowned basin. Warm springs are the expected surface expression of a cooling volcanic system under a flooded basin, which is why the swim exists at all. The frescoes and everyday objects from the buried town now sit in the museum of prehistoric Thera and in Athens.

Two thousand years of lava building the islands

The Kameni islands are young in geological terms, built by eruptions recorded over more than two millennia. The biggest episodes with written or dated lava flows are 1707 to 1712, 1866 to 1870, 1925 to 1928 and 1939 to 1941. Each added land to Nea Kameni, which now spans about 2 km across. The final small eruption was in 1950, forming a lava dome, and nothing has erupted since.

Palea Kameni, the springs island, is the older sibling, so named to distinguish it from Nea, the new one. Sailors and travellers have described the warm waters for centuries, and by the twentieth century the springs swim was a fixed stop on caldera excursions alongside the crater walk. The 2025 earthquake swarm reminded everyone the system is alive, more than 12,800 tremors in weeks and a month-long state of emergency on the main island, but no eruption followed and the boats resumed as normal once activity subsided. The islets remain what they have been since the 1950s, a dormant but monitored volcanic field you can swim beside.

What you pay, item by item

The springs themselves are free. There is no gate, no fee, no ticket booth on Palea Kameni. What you pay for is the boat. Short volcano and springs cruises start at $31.28, catamarans run $67 to $171.61 depending on food, group size and transfers. On top of the boat fare, two extras can appear: the $5.59 (€5) volcano park fee, collected on Nea Kameni only on trips that land there, and transfers if you book a version without pick-up included.

Compare that to land attractions: Akrotiri costs $22.40 (€20), the museums in Fira $11.19 (€10) each. The boat trips look expensive until you remember they bundle transport, guide, and often a meal. If budget is the deciding factor, the volcano, hot springs and Thirassia cruise at $31.28 is the floor, and it still includes two islands. Note that a widely blogged combined archaeological ticket does not exist on any official page, so do not plan around one.

The kit list

Bring a dark or old swimsuit, the iron staining is real. Bring a towel, though the better catamarans supply them. Reef shoes or old sandals help on the rocky shallows near the springs. Sun protection matters more than on land, the caldera reflects light off water and cliffs and there is no shade on any boat deck. A dry bag protects phones and a windproof layer earns its place on evening crossings when the wind drops the temperature fast.

Leave valuables ashore where you can. There is nowhere secure at the springs, you swim from an anchored boat and someone always stays on board to watch bags, but travel light anyway. If you wear contact lenses, the mineral water is an argument for swimming with your head up or wearing goggles. And shower when you get back, the sulphur smell fades with fresh water but lingers on hair all evening otherwise.

The list

Most people arrive knowing only that there is warm water. These five points separate a smooth trip from a disappointing one.

• The water temperature is not published anywhere official, so any exact figure a blog quotes is a guess, the honest answer is warm patches in ordinary sea water facts pack: hot springs water temperature not stated.
• The springs and the volcano crater are separate islands, Palea Kameni for the swim and Nea Kameni for the hike, and landing on the crater adds a $5.59 (€5) park fee collected on the island facts pack: volcano park entrance fee.
• The caldera crossings can be cancelled by weather specifically because of the July and August meltemi wind, which is the stated reason boat trips get called off climate data and operator weather clauses.
• The last eruption was in 1950, so the islands are geologically brand new, built by eruptions in 1707-1712, 1866-1870, 1925-1928 and 1939-1941 facts pack: Kameni eruption history.
• The warm water is orange because of iron, and the same iron stains swimwear, which is why experienced swimmers go in dark suits facts pack: iron-rich warm water in a bay of Palea Kameni.

Morning springs, afternoon sights

Take an early boat from Fira Old Port, done and showered by early afternoon, then spend the rest of the day on land. This pairs naturally with the Fira museums, the museum of prehistoric Thera and the archaeological museum of Thera, both open 08:30 to 15:30 and both $11.19 (€10). If you move faster, a late-afternoon run along the rim from Fira through Firostefani and Imerovigli ends at sunset with dinner on the caldera edge.

This shape suits hot days, because the boat gets you off land during the worst heat and the afternoon sights are indoors or shaded.

Volcano morning, springs midday, beach afternoon

The classic full-day shape: crater walk on Nea Kameni in the morning, springs swim on the way back, then a bus to the black sand for the afternoon. Fira to Perissa costs $3.02 (€2.70) and delivers you to Perissa beach, where the warm-spring swim becomes a footnote to a proper beach afternoon. Alternative: Kamari on the other side of Mesa Vouno, with Ancient Thera on the hill above if you have energy left.

Book this as one boat ticket that covers volcano and springs, then buy the bus leg separately. Total transport for the day stays under $45 per person including the cable car down.

The evening version for short stays

On a two- or three-day trip, the sunset boat is the efficient choice. Spend the day at Akrotiri Santorini or the beaches, then board a late-afternoon catamaran from Oia or Ammoudi for the springs and the sunset from the water. You sacrifice nothing on land, because the boat returns after dark, and the swim in warm water as the light goes is the best-timed version of the experience.

See how this fits a wider plan at Santorini in 2 days or the full Santorini itinerary, and check Santorini in october if you are travelling in the shoulder season, when evening swims need a windproof layer.