Lago Santo parmense, Glacial lake in Corniglio, Italy

Lago Santo parmense is a glacial lake situated within the Tuscan-Emilian Apennine National Park at approximately 1,500 meters elevation. The water is cold and clear, surrounded by steep mountain slopes that shift color with the seasons.

The lake is a glacial basin at 1,506 m in the municipality of Corniglio, the largest natural lake of the northern Apennines. On 12 September 1882 the CAI section of Parma inaugurated a refuge on its shore to shelter hikers; on 11 August 1935 it was named after Giovanni Mariotti, mayor of Parma and CAI president from 1893 to 1935.

Fishing here requires a regional Emilia-Romagna permit for salmonid waters (category D), issued free by the municipal offices, plus a free permit obtained on the lake shore. Angling is allowed on Mondays, Thursdays, Saturdays, Sundays and public holidays. The waters hold brown trout, alpine char, bullhead and rudd, along with insects and crustaceans, some of them endemic.

Visitors can reach the lake from a mountain refuge where a chairlift provides access to the higher elevation. A refuge nearby offers overnight accommodations and meals for those wanting to spend more time in the area.

During winter the lake surface freezes into thick ice that attracts specialized divers who explore beneath it. This unusual activity remains relatively unknown to most visitors and happens only in these high-altitude Apennine locations.