Kotychi Lagoon is the largest Lagoon in the Peloponnese with an area of approximately 750 hectares and an average depth of 0.40 – 1.0 metres. It is situated to the north of the Lehaina region and is separated from the Ionian Sea on the west side by a narrow 5 kilometre length sand strip.

This is a typical Mediterranean Lagoon and is a significant site for the wintering, breeding and migration of water birds, many of which are in dwindling numbers in other regions of the country. In addition to the avifauna, Kotychi Lagoon is a significant migration site and habitat for various fish species until the reproductive period commences when they migrate to the sea. It is accordingly a natural vivarium that operates with traditional fish fertilisation methods.