 FACT: In the opening scene, Jeffs first line is, "Tell me again why  were sitting on top of this rock called Trollsvatn?" The Icelandic  word "vatn" means "lake". Since the volcano they are surveying is a  mountain, it would be more likely to be named "Trollsfell" ("fell"  means "hill" or "mountain", as in the volcano Eldfell). However,  most Icelandic volcanoes have individual names, often taken from the  nearest landform, be it glacier, headland or other formation. There  is one volcanic area in Iceland with the word "vatn" in its name,  but it refers to a volcano with its magma chamber and vent under a  series of frozen