In historical times not so fertile and almost treeless, the plain of Argos now cultivates legumes, cotton, tobacco, olive trees, vineries, vegetables and citrus trees, thanks to the river Erasinos. Tobacco has been somewhat phased out in favour of food products such as its famed melons and citrus fruits. High poplar and plane trees generally appear near the river, while shrubs and olive groves lie on the surrounding mountains. The plain is dotted with springs here and there, some of which are connected to the sea via underground tunnels. If it weren't for this, the plain would have flooded during certain months and would have become a lake.
An outstanding place of natural marvels and historic sites, the Katafyki Gorge just 6 kilometres outside Ermioni has a lot to offer. Amazing caves and rocks alternate with running water and lush vegetation. You will also come across the church of Agios Nikolaos from 1740. Wander around the old bridge were much of the nature is concentrated, then make your way to the village of Fourni for a rest stop. The gorge is 4.5 kilometres long. In New Epidaurus lies the Vothylas gorge at the outer limits of the village.
The Erasinos river in Kefalari was once called Stymphalos after the lake which was its source. Not far from the source are the remains of the temple of Artemis and a cave, as well as an altar where sacrifices to Panas and Bacchus were made. The cave has a little church of Zoodochos Pigi, a very old temple established there as there used to be a crypt in the cave. The church was destroyed and later rebuilt by Greek immigrants in the state of Georgia in the US who originated from Argos.
The Lake of Lerni in the Municipality of Argos has its source from the nearby mountains of Arkadia. It is supposedly where the seven headed Hydra originated in Greek mythology and was killed by Hercules. Also in the same municipality near Kyveri there is the Deini or Anavalos spring resembling artesian wells, and where there used to be a temple of Genesios Poseidon. The most notable springs in the area are at the source of the Akova.