A kilometre and a half to the south-east of the village of Agios Georgios (Saint George), opposite the Elaphonisos island, is Strongyli Limni (the Round Lake), which is an important biotope.

This is a lagoon, and is continued along the seashore with two other smaller lakes, Manganos and Nerantzionas.

Around the lake, on the side towards the sea, there are chamber tombs of the prehistoric period, and in the depths of the sea, in front of the seashore with the tombs, opposite the Pavlopetri islet, is a whole prehistoric town. This was discovered in 1968 and became known world-wide after research by the Institute of Oceanography of the University of Cambridge. The lake is now a recognised wetland and has been included in the European Union's NATURA 2000 programme.

The flora around the lake and on Elaphonisos is of importance and includes a rare and threatened species of cedar. It should be added that in the Vatika area, three plant species unique in the world were found by the distinguished botanist Constantinos Goulimis: the Goulimis tulip, flax Hellenica, and the Linum leucanthemum thyme, with purple or red leaves.

The Caretta-caretta turtle is a frequent visitor to the sandy beaches.

Where Maleas projects into the sea, there is monument of nature of world importance: the famous petrified forest which stands near the sea and impresses the visitor with tree trunks millions of years old. The ground in which they stand is made up of a vast number of fossilised shells which create a kind of natural mosaic.