This view is looking down into the passage of Blue Grotto Cave. Material from the breakdown near the entrance to the lava tube was used to line the trail. Note the naturally stable dome shape of the passage. In many parts of the lava tubes the walking surface consists of lava that hardened on the floor of the tube. The lava tubes that are accessible to the public range in length between a few hundred to a few thousand feet; many of the tubes are interconnected.

The URL is: https://gotbooks.miracosta.edu/gonp/labe12/6/2010/html2/lava170.htm Last modified: 12/6/2010