Marathonisi — Turtle Island: How to Visit, and What the Boats Can and Can't Do
Marathonisi is the turtle-shaped islet where loggerheads nest. Marine Park rules, honest odds of seeing a turtle, the Keri Caves pairing and which boat to book.
Marathonisi is the small, pine-covered islet in the middle of Laganas Bay that every south-coast boat on Zakynthos circles, and that tour listings call Turtle Island for two reasons: it is shaped like one, and loggerhead turtles nest on its beach. It sits inside the National Marine Park, two nautical miles off both Laganas and Keri, and it is the reason the Keri Caves trips exist in the form they do — the caves and the island are one bay, so the boats do both. This page is about the boat-trip decision, not turtle biology.
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What Marathonisi is, and what the rules mean for you
The islet is a protected nesting beach in the Mediterranean’s most important loggerhead colony: Laganas Bay’s six beaches hold an average of around 1,200 nests a year. That protection is the whole shape of a visit. You can land, but only on the sandy strip on the side facing Laganas, and the park sets the terms.
| Rule | What it means on the day |
|---|---|
| Landing from 07:00 until sunset only | No evening stops; sunset cruises look, they don’t land |
| Stay within about 5 m of the water’s edge | The dunes and the back of the beach are nests — off limits |
| No umbrellas, no sunshades, no fires, nothing left behind | Bring a hat; there is no shade and no facilities |
| Boats keep about 15 m from a turtle and to a slow speed in the protected zones | The “get close” photos are taken from the boat, at the boat’s pace |
| Visitor cap (200 on the island at once) | Mid-morning in August the beach is busy; earlier is calmer |
The island has no bar, no loos, no shade. One operator’s listing mentions buying snacks there — treat that as unreliable and bring your own water. The 30-minute swim stop most trips allow is enough: a swim off a white beach with the caves of the islet’s far side and the Keri cliffs behind.
Seeing a turtle — the honest version
Loggerheads nest here from mid-May to August and the hatchlings emerge from late July into autumn; adults are in the bay from roughly May to October, which is also the boat season. Most trips see at least one turtle surfacing to breathe, and the glass-bottom boats sometimes catch one passing underneath. But sightings are a matter of the day, the light and the boat’s patience, and the park’s distance rules mean a turtle is a head and a shell at 15 m, not a snorkel encounter. Any listing that promises “guaranteed” sightings is describing its usual luck, not a contract. If the turtle is the whole point, a dedicated Turtle Spotting Boat Trip in Laganas Bay ($17, 20–30 minutes on the water) is a cheap, focused option; the transparent kayak and SUP turtle-spotting trips ($84) are the quiet, engine-free alternatives.
Agios Sostis and Cameo Island
Nearly every Marathonisi boat leaves from Agios Sostis, the harbour at the western end of Laganas — 2.5 km from the resort centre, a few minutes by taxi, and the meeting point for the hotel-pickup trips. Beside the harbour is Cameo Island, a rocky islet reached by a wooden footbridge, with a pebble beach and a small entrance fee (around €5 in recent seasons). Several tours make a photo stop at Cameo from the water; you can walk over yourself before or after your boat.
Which boat to take
| Trip | From | Time | Price | Best for |
|---|---|---|---|---|
| Glass-bottom boat: Turtles, Marathonisi & Keri Caves | Laganas / Agios Sostis, pickup | 3 h | $32 | Families; watching the water beneath you |
| Speedboat: Turtles, Marathonisi & Keri Caves | Agios Sostis, pickup | 3 h | $32 | Getting inside the caves |
| 4 h Turtle, Keri Caves, Mizithres & Eros Cave | Agios Sostis | 4 h | $47 | The longest loop, two extra stops |
| Agios Sostis: Marathonissi, Keri Caves & Turtle Spotting | Agios Sostis, no pickup | ≈3 h | $29 | Lowest price |
| Turtle Island and Caves Private Boat Trip | Agios Sostis | 3 h | $276 per boat (2) | A private skipper for a couple |
The glass-bottom boat is the natural Marathonisi choice — 2,907 reviews at 4.4, a steady hull for children and anyone unsure on the water, and a floor you can watch for turtles while the captain looks for them on the surface. Our breakdown → The speedboat is the same price and the better choice if the caves matter more than the island. Our breakdown →
Two larger-boat excursions are widely sold — Marathonisi, Cameo Island and Keri Caves Tour and the Half-Day Tour to Turtle Island and Keri Caves, both $65 — with more reviews than the small boats but lower ratings (4.2), which is the usual trade of a bigger boat: comfort and a toilet against distance from the caves.
The Keri Caves pairing
Because the island and the caves share a bay, almost no boat does one without the other, and the Keri Caves are where the swimming happens. If you want to weigh the two halves against each other — or against the northern trip to the Blue Caves and Shipwreck Beach — the north vs south guide does that, and the whole southern inventory is compared on Keri Caves + Turtle Island tours.
Frequently asked questions
Can you land on Turtle Island?
Yes, in daylight — between 07:00 and sunset — on the narrow strip of beach nearest the water. Walking inland, umbrellas, fires and staying after dark are prohibited, and there is a cap on how many people can be on the island at once.
Is it guaranteed that I will see a turtle?
No. Sightings are likely in season (roughly May to October) but never certain, and boats must keep about 15 m from any turtle. Choose a boat with a glass floor or a dedicated spotting trip if the turtle is your priority.
How do I get to Marathonisi?
Only by boat. Organised trips leave from Agios Sostis harbour at Laganas, small boats from Limni Keriou, and licence-free rental boats from either. It is about two nautical miles offshore.
How long do boats stop at the island?
Around 30 minutes on most three-hour trips — enough for a swim and a photograph. There are no facilities and no shade, so bring water and a hat.
What is the difference between Marathonisi and Cameo Island?
Marathonisi is the protected nesting islet in the middle of the bay, reached by boat. Cameo is the small rocky islet beside Agios Sostis harbour, reached on foot over a wooden bridge for a small fee; many boats pass it on the way out.
When is the best time of year?
June to September for warm water and the highest chance of turtles; the nesting season runs mid-May to August and hatchlings appear from late July. Mornings are calmer and less crowded on the island.
Ready to book? Every Marathonisi trip is compared on the Keri Caves + Turtle Island tours page, or check availability for the glass-bottom boat above.
Pick Your Coast, Then Book
North for the Blue Caves and Shipwreck Beach, south for the Keri Caves and Turtle Island. Every trip we list has free cancellation on most dates — compare them side by side before you commit.
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