Lago Epecuén, Salt lake in Buenos Aires Province, Argentina.

Lago Epecuén is a salt lake in Buenos Aires Province with salt concentration roughly ten times that of the ocean. The lake is ringed by the remains of Villa Epecuén, whose ruins have emerged from the water since 2009 and are covered in salt deposits.

The lake was first named in 1770 by Royal Navy pilot Pablo Zizur, who called it San Lucas. By the early 1800s its mineral waters were already famous for curative properties, and in 1886 an analysis found salinity ten times that of the sea. The 1920s brought development of bathing facilities, and on 10 November 1985 the lake overflowed and completely flooded Villa Epecuén.

The lake drew visitors from the early 1900s onward, who came seeking relief from rheumatic and skin ailments in its mineral-rich waters. This wellness tradition shaped how people understood the place for decades.

Visitors can explore the ruins of Villa Epecuén, which are covered in a thick layer of salt that tells the story of the flooding. The area is best visited during warmer months when conditions are more comfortable for exploring.

On 29 January 2017, 1,941 people floated on their backs in the salt water holding hands, a Guinness World Record for the largest such gathering; Taiwan had held the previous record with 643 people in 2014.