Marathonisi Island

The name Marathonisi refers to the island’s shape: a rounded “shell” with a narrower neck of land toward Keri. From the viewpoint at Keri Lighthouse or from a boat in the bay, the resemblance to a swimming turtle is unmistakable, which is why locals and tour operators alike use the name Turtle Island.

The islet is uninhabited and has no roads or permanent buildings. Everything you see is natural: juniper and low scrub on the ridges, white pebble sand on the main beach, and limestone caves along the shoreline that boats can enter on calm days.

The main beach on the east side faces the open bay with deep blue water and fine white sand, a classic Mediterranean scene that fills with day boats in summer. Around the sides of the island, smaller coves appear between the rocks, many reachable only from the sea. At the back, larger caves open into dark chambers perfect for swimming, snorkelling and photography.

Our Turtle Island & Keri Caves cruise and the Turtle Island Cruise & Sunset Tour both include time at Marathonisi with swimming stops and a slow loop of the coastline. Keri Caves, on the mainland opposite, are usually visited on the same trip for a full south-west Zakynthos boat day.

Marathonisi is a core nesting site within the National Marine Park of Zakynthos, established to protect the loggerhead sea turtle (Caretta caretta). Females lay eggs on the sand from late May through August; hatchlings emerge through October. Access to certain zones is restricted during nesting season, and visitors must not use umbrellas, chairs or lights on protected areas.

Thermal conditions on Marathonisi’s main beach mean that most hatchlings here are male, while other Laganas Bay beaches produce more females. That makes the islet scientifically important as well as beautiful. Always follow crew instructions, keep noise low and never touch turtles or nests. Responsible tourism keeps Turtle Island open for future generations.