The Açores (Azores) are well known to the Europeans: they are very often mentioned in the weather forecast as the weather on the Atlantic has big influences on the weather in Western and Central Europe.

The Azores are located in the middle of the Atlantic ocean, right between Lisbon and New York, about 1,600 km from the European Continent. The archipelago consists of nine islands and a few islets. The main islands are São Miguel, Santa Maria, Terceira, Graciosa, São Jorge, Pico, Faial, Corvo, and Flores.

The ground is here 3,500 m below sea level. The islands are enormous volcanoes rising from the bottom of the sea a little bit more than those 3,500 m, and just the summit of every mountain is above the water level.

The islands are mainly of volcanic origin, the caves found here are volcanic caves (lava tubes). The geology is not suitable for karst and karst caves. Still there are some exceptions. Some small patches of tertiary limestone, uplifted by the volcanic activities, are karstified and contain caves.