Limni Vouliagmenis is a natural thermal lake about 20 kilometres southeast of Athens, Greece. The lake is in Vari-Voula-Vouliagmeni, near the seaside resort town of Vouliagmeni.

The lake is fed by underground thermal springs rich in minerals, and its water is known for its therapeutic properties. In addition, the temperature of the water remains constant throughout the year, averaging around 22-29°C (71-84°F), making it an ideal spot for year-round swimming and relaxation.

A rocky, forested area surrounds the lake with several small beaches and coves along its shoreline. There are also several cafes and restaurants where visitors can enjoy a meal or a drink while enjoying the scenic views.

Limni Vouliagmenis is a popular tourist destination in Greece and attracts visitors from all over the world who come to enjoy its natural beauty and therapeutic waters. The lake is also a protected natural monument home to various plant and animal species, including fish, turtles, and birds.