Submitted by: Yuri Klitsenko
As the story goes, some monks in Rusaki monastery near Murom were involved in romantic relations with mermaids.
Mermaids seduce humans in order to drown them. Thus Rusaki monastery, which stood near the lake, had sunken and the new lake appeared on the spot.
The Sviatoe Lake of sunken monks and mermaids is located near villages Dedovo and Korobkovo.
Dedovo is famous for its parish church, which preserved the Holy Sweat of Martyr Catherine, the Early Christian saint, and the wonderworking icon of Christ found in the lake.
(I think that "the Holy Sweat" is actually some fragrant oil from St. Catherine's shrine).
Yuri Klitsenko is a Russian living in Moscow. He works for the Russian Orthodox Church.