Korinthia has a few uninhabited islets, called the Alkyonides (Prasonisi, Glaronisi Zodohos Pigi and Daskalio) in addition to others, which could be interesting to visit. It is a mountainous prefecture with the mountains on the western side being the highest. These include Ziria or Kyllini, Saita and Oligyrtos). There are very green regions in the Gerania mountains and in Onia. Sitting under the cherry trees in Evrostina is an experience in itself.
The dried up lake of Stymphalia (see below) on the Peloponnese side and salty lake of Vouliagmeni near Loutraki on the mainland side offer great escapes. The latter was actually an underground cave once upon a time which collapsed to yield a lake.
Designated as a protected site for fauna and flora under the EU's Natura 2000 programme, Lake Stymphalia is more of a wetlands area surrounded by lovely mountains. The lake area is teeming with amphibians, birds and plants, considered a breeding place for 133 species of rare birds and fowl. It is also home to a unique species of fish called Taxom Pseudophoxinums which sinks itself into the muddy waterbed of the lake during dry periods and creates a kind of slippery envelop around it for protection. There are also visible parts of an ancient Roman aqueduct from Hadrian's time, which used to carry water to Ancient Corinth. In mythology, the lake is where Hercules slew the man-eating Stymphalian birds. Today, the modern town of Stymphalia (or Stymfalia) is taking efforts to preserve the wetlands and lake.
If Stymphalia doesn't have much water, Lake Doxa is full of it. That's because the lake was created artificially by damming the area. Looking quite natural, the lake is surrounded by pine and other forests against a backdrop of the Chelmos mountaintop (or Aroania). Noteworthy are the churches of Agios Fanourious and the monastery of Saint George which was moved to a higher location as the lake was developed in the 1990s. While there aren't too many modern roads around it, there are plenty of hiking paths.