The Lech Sant (Lech Sant in Ladin, Lago Santo in Italian) is a lake, protected natural monument in South Tyrol, located in the municipality of Santa Cristina Gherdëina.
Lech Sant translated into English becomes Holy Lake and the origin of this name is linked to a popular legend.
Geological and archaeological research conducted in 1984 uncovered two distinct prehistoric stratifications on the site, dating respectively to the Bronze Age and the Iron Age. It seems plausible to assume that the site was used during these periods by the earliest populations of the area as an ancient place of worship.
The small mountain lake is located on the Alpe di Mastlè, above the settlement of Santa Cristina.
The biotope is notable for its location and biodiversity. Its origins date back to after the Würm glaciation and its waters are home to the minnow, a small freshwater fish adapted to cold, oxygenated waters.
According to popular tradition, long ago where the lake now stands, there was a small church. Some local shepherds are said to have desecrated the sacred site with their nocturnal festivities and, as punishment, were made to sink along with the entire church, giving rise to the depression that later became the lake.