Lagoa do Fogo, Volcanic crater lake in São Miguel Island, Portugal.

Lagoa do Fogo is a volcanic crater lake on São Miguel Island in the Azores, nestled within a large volcanic massif. The water body is surrounded by steep slopes and sits at an elevation overlooking the surrounding volcanic landscape.

The caldera of the Água de Pau Massif, the youngest volcano on São Miguel, formed about 15,000 years ago, with its present shape set by a collapse at the summit roughly 5,000 years ago. The last eruption occurred in 1563. The area became a protected reserve in 1974 by Decree-law 152/74, and the Reserva Natural da Lagoa do Fogo was created in 1982 under Regional Decree 10/82/A.

The lake's name, "Lake of Fire," comes from the volcano that formed it. In September 2012 its beach was named one of the 7 Wonders of Portugal in the Wild Beach category. The crater lies within the parishes of Conceição, Matriz and Água de Alto.

Visitors can reach the lake from various vantage points or via hiking trails, with some routes involving steep sections. Good footwear and weather-appropriate clothing are important, as conditions at this elevation can change quickly.

The lake supplies drinking water to settlements on the southern slopes of the caldera, and its only two permanent outflows run west toward Barrosa and south-southeast. No buildings or human activity exist inside the crater, and the surrounding land is held in parcels averaging 283 hectares.