La Cueva de los Verdes, in the northern part of Lanzarote, to the south-east of the volcano Monte de la Corona, forms part of a spectacular system of underground grottoes (the jameos). It is not only one of the most interesting volcanic formations on the island, but is also one of the longest volcanic galleries in the world (6 km long).
The caves and galleries were created as a result of a prehistoric eruption from the volcano Monte Corona between three and five thousand years ago when a major stream of lava was ejected toward the east coast into in the sea.
The surface of the lava cooled rapidly and hardened, whilst steaming lava continued to flow underneath the petrified basaltic layer.