The Natural Monument Gruta das Torres, on Pico island, a volcanic cavity that owes its origin to basaltic pahoehoe lava flows, is the largest lava tunnel known in the region, with about 5150 m in total length and a maximum height 15 m.
The Natural Reserve of Pico Mountain, the highest mountain of Portugal and the third highest in the North Atlantic, is an impressive stratovolcano, which exercises its dominion over the landscape of the island of Pico.
The Natural Reserve of Faial Caldeira, once, it was also a stratovolcano very similar to what the Pico Mountain is today, but about 16,000 years ago the volcanic cone started to collapse.
A process that came associated with an explosive volcanism, creating the geological depression we know today at Faial Caldeira, offering a set of natural habitats that represent 65% of Azorean endemic flora.
The Natural Reserve of Morro de Castelo Branco, a traquitic dome that forms a peninsula on the south coast of Faial, is also one of the most unique Geosite in the Azores. This is an important site for seabirds nesting and, therefore, a great place to experience the night singing of Shearwaters.
The Partial Natural Reserve of Lagoa da Fajã da Caldeira de Santo Cristo, in São Jorge island, is a wetland of high biodiversity, whose formation is linked to the origin of the fajã, which occurred due to a massive landslide after an earthquake in the 18th century. Its morphology associated with a very particular sociocultural history, due to the difficult access of the fajã, makes it one of the most impressive sites of the Azores.