A caldera is a geological term for a large, roughly circular or elliptical depression created by the collapse of a volcano’s summit after a high-magnitude eruption that fully or partially empties the underground magma chamber. Unlike common volcanic craters (smaller and formed directly by explosion), calderas can reach several kilometres in diameter and hundreds of metres in depth.
In the Azores, thanks to the intense volcanic activity that shaped the archipelago over millions of years, some of Europe’s most impressive calderas are found. Many of them, over time, accumulated rainwater and springs, giving rise to beautiful high-altitude lakes. Iconic examples include:
- Caldeira das Sete Cidades (São Miguel) – home to the famous Blue Lake and Green Lake
- Caldeira Velha (São Miguel)
- Caldeira do Faial (Faial Island)
- Caldeira de Santo Cristo (São Jorge)
- And, of course, Caldeira do Mosteiro on Flores Island, where the Calmos project is located – one of the deepest and least known, with over 500 metres of depth and nearly vertical walls covered in lush endemic vegetation.
These calderas are true natural amphitheatres, authentic biodiversity sanctuaries, and places of almost mystical beauty, where silence and the force of nature meet.
