Palea Kameni Hot Springs: The Swim-To Thermal Springs Guide

No dock, no path, just a swim

Palea Kameni is the quieter of the two black islets sitting in the middle of the Santorini caldera, and it works completely differently from its neighbour. There’s no jetty, no landing point, and nowhere to walk. Every caldera cruise that stops here anchors a short distance offshore, and getting to the hot springs means swimming — a few dozen strokes from the boat to a patch of warmer, mineral-tinted water pooling near the rocks at the island’s edge.

That single fact changes how you should prepare for the stop. This isn’t a beach visit or a guided walk like the one over on Nea Kameni; it’s a swim stop, full stop. If you’ve read the Nea Kameni volcano guide and expected something similar here — a ticket booth, a marked trail, solid ground underfoot — Palea Kameni will surprise you. There’s nothing to buy and nothing to walk on. You come prepared to get in the water, or you stay on the boat and watch.

What the water actually feels like

Call it warm, not hot. As you swim closer to the rocky shoreline where mineral-rich water seeps out from beneath the islet, you’ll notice distinct pockets that are noticeably warmer than the surrounding sea, sometimes uncomfortably so if you linger right at the source, but nothing close to what “hot spring” tends to suggest elsewhere in the world. There’s no steam rising off the surface and no need to ease in gradually the way you might at a thermal bath. It’s closer to swimming through patches of bathwater-temperature sea mixed with the cooler Aegean around it.

The colour is the giveaway before the temperature is. The water near the springs takes on a cloudy, rust-orange tint from dissolved iron oxide, quite different from the clear blue you’ll have been swimming in minutes earlier. Some visitors find the smell — a mild sulphur note — more noticeable than the heat itself. None of it is unpleasant, but it is unmistakably mineral water rather than a resort pool, and it’s worth setting that expectation before anyone jumps in expecting a spa.

The detail nobody tells you before it’s too late

Here’s the part every operator should mention and not all of them do: that same iron content stains fabric, and the stain doesn’t wash out. Light-coloured swimwear — white, pastel, pale grey — comes back from Palea Kameni with a rusty, orange-brown tint that soap and a normal wash cycle won’t fully lift. It isn’t dirt; it’s a mineral dye, and it sets into the fibres almost immediately.

The fix is simple and worth planning before you leave your hotel room: wear a swimsuit you don’t mind marking, ideally something already dark-coloured or already a few seasons old. Save the new white bikini or trunks for a different swim stop on the same cruise, most of which include at least one clear-water break elsewhere in the caldera. If you only own light-coloured swimwear, consider swimming in a rash guard or cover-up over it, or simply accept the stain as part of the souvenir — plenty of returning visitors treat it exactly that way.

What to pack for this specific stop

Item	Why it matters here
Dark or old swimwear	Iron-rich water stains light fabric permanently
Water shoes	The volcanic rock underwater is sharp in places
Waterproof phone case	You’re swimming, not wading — a loose phone goes down
A towel you don’t mind marking	Wet swimwear can transfer a faint tint
Change of clothes	For the rest of the cruise after you’re back aboard
No fine jewellery	Mineral water can dull rings, chains and watch finishes

Most boats provide life jackets or pool noodles for anyone who prefers not to swim unassisted, and crews are used to helping less confident swimmers make the short distance to the warm patch and back. If you can’t swim, or would rather not, staying aboard and watching from the deck is a completely normal choice — nobody is required to get in.

How this fits into a caldera cruise

Palea Kameni almost never appears as a stand-alone destination. It’s one stop — usually the swim stop — on a longer route around the volcanic islets, typically paired with a landing at Nea Kameni for the crater walk described in the Nea Kameni volcano guide. A typical order runs: cruise out from the old port of Fira or Ammoudi Bay, land and walk the crater at Nea Kameni, then re-board and sail the short distance to Palea Kameni for the swim.

Because the two islets sit so close together in the middle of the caldera, cutting one out rarely saves meaningful time, and most operators build both into a single afternoon or sunset itinerary. If you’re deciding between cruise formats, the comparison of Santorini volcano tours breaks down which itineraries include both stops, which skip the crater walk, and which run the hot springs swim as the sole volcanic element before heading on to Thirassia or a sunset viewing point.

One of these routes is a day-time catamaran cruise built around exactly this pairing:

a daytime catamaran cruise with swim stops and a barbecue lunch on board, which anchors at both islets before continuing on to open-water swim spots elsewhere in the caldera.

Sunset versus daytime at the springs

The water temperature and the stain risk are identical whether you visit at midday or at sunset — the springs don’t change by time of day. What changes is the light, the crowd, and what else the cruise wraps around the stop. A sunset sailing tends to treat Palea Kameni as an earlier waypoint before the boat repositions for the evening’s main event, described in full in the Santorini sunset guide and the dedicated sunset cruise comparison. One popular version pairs the springs swim with a full evening on the water:

a sunset catamaran cruise with swim stops and a barbecue dinner, which visits the volcanic islets in the afternoon light before settling into position for sunset later on.

A midday sailing, by contrast, usually gives more unhurried time in the water since there’s no fixed sunset clock to work around. If your priority is simply the swim itself rather than the sunset finale, a straightforward loop works well:

a catamaran cruise around the volcanic islands, which circles Nea Kameni and Palea Kameni without building the day around an evening arrival time.

Shorter options if time is tight

Not every visitor has a full afternoon or evening to spend on the water. For a compressed version that still includes the swim, a shorter format exists:

a three-hour caldera catamaran cruise with drinks, which fits a Palea Kameni swim stop into a tighter window, useful for anyone splitting a day between the boat and time in Fira or Oia.

Whichever length you choose, check the itinerary description before booking rather than assuming: some shorter cruises swap the Palea Kameni swim for a different anchorage closer to the caldera’s cliffside villages, and the hot springs stop specifically is what distinguishes this excursion from a general sightseeing sail.

Getting oriented: what you’re actually looking at

Palea Kameni and Nea Kameni are both remnants of the same volcanic system that produced the Bronze Age eruption responsible for the caldera itself — the background on how that came to be is covered in how the Santorini caldera was formed. Palea Kameni is the older of the two islets, and its hot springs are a passive seep of mineral-rich water rather than an active vent — there’s no comparison to the crater you’d see on the Nea Kameni walk, and no sense of standing near live volcanic activity while you swim.

For context on the volcano’s more recent history, including the seismic activity that made headlines in early 2025, the Santorini safety and the 2025 earthquakes guide lays out the facts plainly: a weeks-long earthquake swarm between Santorini and Amorgos, no eruption, and no ongoing risk tied to a routine swim at these springs today.

Practical notes before you book

A few things worth confirming with whichever operator you choose, since details vary slightly between boats:

• Life jackets or flotation aids: most crews carry them for anyone unsure about the swim distance, but it’s worth asking in advance if you’d specifically like one.
• Ladder access: catamarans generally have an easier boarding ladder back up than smaller sailing boats — a consideration if you or someone in your group has mobility concerns, covered more broadly in accessibility in Santorini.
• Combined itineraries: many boats pair this swim with additional stops at open-water swimming spots or a look at Thirassia from the water, so read the full stop list rather than assuming Palea Kameni is the only swim break.
• Weather: the meltemi wind can affect anchoring conditions around the islets in summer; the meltemi wind explained guide covers when it’s most likely to disrupt a sailing.

None of this requires advance planning beyond the swimsuit choice and a waterproof phone case. The springs themselves ask nothing of you — no ticket, no trail, no fitness requirement beyond a short swim — which is exactly why they work as an easy, memorable stop on almost any caldera cruise out of Santorini.

How deep can you swim at the springs

The water around Palea Kameni’s hot springs isn’t uniformly shallow. Close to the rocks where the mineral seep concentrates, the seabed sits at a swimmable depth for most adults, deep enough that nobody stands on the bottom, but not so deep that a confident swimmer needs to work hard to stay afloat. Further from the warm patch, the sea drops away more sharply into open caldera water, so it’s worth staying within sight of the boat and the group rather than drifting toward open water chasing a stronger current of warmth. Crews generally mark the safe swimming perimeter verbally rather than with buoys, so listen for instructions before you jump in, especially if visibility is hazy from the mineral tint that day.

Palea Kameni hot springs: your questions answered

Do we get off the boat at Palea Kameni?

No. There’s no dock and no path here. The boat anchors offshore and you swim to the warm patch of water near the rocks, then swim back. Everything you do at Palea Kameni happens in the sea.

How hot is the water, really?

Warm, not hot. Close to the rocks where the mineral water seeps in, you’ll feel noticeably warmer pockets against the cooler sea around them, but nothing close to a hot spring you’d associate with steam or scalding water.

Will it stain my swimsuit?

Yes, and durably. The water carries dissolved iron that leaves a rusty, orange-brown tint on light fabrics. Dark or already-old swimwear is the safer choice; a favourite white bikini is not.

Is there an entrance fee for Palea Kameni?

No. Unlike Nea Kameni, which charges a small cash entry fee for the crater walk, Palea Kameni has no ticket and nothing to pay on site — the springs are simply part of the swim stop most caldera cruises include.

How is this different from Nea Kameni?

Nea Kameni is the neighbouring islet with the active crater: you land, pay a small cash fee, and walk about 30 minutes over volcanic ash to the rim. Palea Kameni is swim-only, with no landing and no fee — most itineraries visit both back to back.

What should I bring for the swim?

A swimsuit you’re not attached to, water shoes for the sharp volcanic rock underwater, and a change of clothes for after. Skip white or pastel swimwear if you want to avoid a permanent souvenir.

Can I wear jewellery or take a phone in?

Leave fine jewellery on the boat — the mineral water can dull metal — and only bring a phone or camera in a proper waterproof case, since you’re swimming, not wading.

Is the water safe to swim in?

Yes, it’s a normal part of caldera cruise itineraries and swum by large numbers of visitors daily in season. It isn’t a spa treatment or a medicinal bath, just a natural warm patch of mineral-rich sea.