Right opposite Limni Kerriou beach, in the southern part of the island and on the west part of Laganas bay you will find uninhabited Marathonisi (also known as Marathia's island), shaped like a turtle.
Its sandy beach that goes into the Ionian sea is visited by the Caretta-Caretta turtles to lay their eggs and for this reason the whole area is part of the National Sea Park created to protect these turtles.
There are two small caves on the pebbly beach in the southern part of the island. Apart from beaches, Marathonisi also has rich vegetation and one can see many olive trees, pine and oak trees and a lot of fennel (maratho), that gives the island its name.
You can visit Marathonisi on a small boat available at Laganas or Limni Keriou.