If swimming pools and ponds have become too mainstream for a quick swim, perhaps it’s time to take a dip in the crater of an ancient submerged volcano, such as this natural lagoon on the Islet of Vila Franca do Campo in Portugal.

Top Places in Portugal

Lisbon, Portugal

Carmo Convent Ruins

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

38.7121, -9.1404

Added by Annetta Black

Labruge, Portugal

Praia de São Paio

Iron Age runes and ruins hide in plain sight along this Portuguese beach.

41.2832, -8.7313

Added by Shaheen Alikhan

Braga, Portugal

Bom Jesus do Monte

A stunning 18th-century site where pilgrims ascend by a series of punishing stairs only to return via funicular.

41.5546, -8.3775

Added by littlebrumble

See more things to do in Portugal »

This tiny island is a rocky crater formation off the coast of Sao Miguel. Its main attraction is the circular lagoon on the islet, which is broken up by a tiny channel that connects it with the ocean. The result is a clear and calm pool that is perfect for swimming and diving. 

The islet and this natural pool are accessible only during the summer and their stunning geography has made them a popular destination. Erosion through continuous exposure to wind and water have created different rock formations around the islet, including a fascinating column-like structure.

Over the years, the islet has helped whalers spot their targets and has also served as a military fort. In 1983, the unique location was declared a nature reserve to protect the endemic vegetation around the crater, as well as the crustaceans and birds who have made the islet their home.