Cueva de Los Verdes in Lanzarote is an open cavity of 1 km in length and is the most spectacular part of a lava tube along almost 8 Km. Despite the name, there's nothing green in this cave: it is called so because about 200 years ago it was considered the property of a family of local pastors, the Verdes. At this point you can see the reflection of the cave on a pond of water completely still, so as not to be perceived at first.