The Gruta das Mercês (identified as Gruta das Mercês I by geologists) is a cave located along the ''Canada das Mercês'', situated in the

civil parish In England, a civil parish is a type of administrative parish used for local government. It is a territorial designation which is the lowest tier of local government. Civil parishes can trace their origin to the ancient system of parishes, w ...

of Feteira,

municipality A municipality is usually a single administrative division having municipal corporation, corporate status and powers of self-government or jurisdiction as granted by national and regional laws to which it is subordinate. The term ''municipality' ...

Angra do Heroísmo Angra do Heroísmo (), or simply Angra, is a city and municipality on Terceira Island, Portugal, and one of the three capital cities of the Azores. Founded in 1478, Angra was historically the most important city in the Azores, as seat of the Roma ...

, in the Portuguese archipelago of the

Azores The Azores ( , , ; , ), officially the Autonomous Region of the Azores (), is one of the two autonomous regions of Portugal (along with Madeira). It is an archipelago composed of nine volcanic islands in the Macaronesia region of the North Atl ...

. The cavern was created by volcanic forces that generated a

lava tube A lava tube, more rarely called a pyroduct, is a 'roofed conduit through which molten lava travels away from its vent'. If lava in the tube drains out, it will leave an empty cave. Lava tubes are common in low-viscosity volcanic systems. La ...

, along a series of lava flows near the coast. It is approximately long, tall and wide.

References

Angra do Heroísmo Gruta Merces Lava tubes {{Azores-geo-stub