New 3D mapping technology has revealed that the island of Rum was once a volcano up to 10,000 ft high.
The same study has also revealed that the island still sits on a six-mile-long fissure which effectively splits Rum in two and is several kilometres deep.
This Loch Long Fault was the "birthplace" of the island, through which countless millions tons of magma poured to create a volcano that was once the size of Mount Etna.
Erosion by rain and wind over a period of 60 million years has reduced the mountain to what remains the highest point today - 2664ft Askival.
The team, from Uppsala University, Sweden, were even able to pinpoint the location of a 500 metre wide magma chamber.
Researcher Valentin Troll said: "The data shows that the fault was active a long time ago. It's the birthplace of Rum."