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 below districts and counties, or their combined form, the unitary authority ...

of Feteira,

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

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 ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...

. The cavern was created by volcanic forces that generated a

lava tube A lava tube, or pyroduct, is a natural conduit formed by flowing lava from a volcanic vent that moves beneath the hardened surface of a lava flow. If lava in the tube empties, it will leave a cave. Formation A lava tube is a type of lava ca ...

, 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