The island of Marathonissi is a small island south of the larger island of Zakynthos. It is situated in the National Marine Park of Zakynthos in the bay of Laganas, which was established here with the intention to protect the sea turtles. The sandy beaches of the island Marathonissi is used by the turtles to lay their eggs. The island has two beaches: a beach of fine white sand and a beach with pebbles. Seals sometimes also visit the island.

Marathonissi is an uninhabited island which is green and covered with pines, olive trees and oaks. From the village of Keri on the island of Zakynthos it is possible to visit the island with a day trip, but it is also possible at not too high costs to rent your own motorboat and visit the island by yourself. There are no facilities Marathonissi (so also no tavern). It is therefore recommended to bring something to eat and bring some water if you want to go and see the island. Also interesting are the sea caves of Marathonissi. It is a popular place for people to snorkel and look at the sea turtles that swim around the island.