The green lake El Golfo

In The Howling Professor series, Adriaan dives into a green lake in search of the entrance to the cave where the professor is hiding. This is the lake El Golfo. It is a major tourist attraction on the island of Lanzarote. The lake turns green because of the algae in the water. The rocks around this lake have also been used for other scenes, such as the scene where Bassie is alone with Robin and is spotted by the professor.