The plain of Feneos has intermittently been a lake in the past, reaching a maximum extent of 194,000 stremmas. This occurred because the two rivers of the Feneos valley, Olvios and Doxa, couldn’t find an outlet to the sea, causing their waters to accumulate in the Feneos plateau. Over time, large chasms, known as sinkholes, formed at the southern ends of the plateau, solving the problem of water accumulation from the two rivers.

However, during certain periods, these sinkholes would close, gradually forming marshlands which eventually turned into a lake. The Feneos Lake and its sinkholes were sources of myths and stories in ancient times, highlighting their significant role in the lives of the Feneans. Additionally, the lake prompted numerous relocations of local settlements, as evidenced by place names such as Kalyvia.

The last time the sinkholes opened was in 1897, drying up the lake and providing large areas for cultivation to the impoverished residents. Since then, the lake has not reappeared except seasonally, gathering small amounts of water in the subterranean channels of Saita.