There are legends relating to Teide, the Guanches aborigines believed that their devil (Guayota) trapped their god of light (Magec) inside the volcano. The supreme god Achaman then fought Guayota and imprisoned him inside the volcano. This story is quite similar the legend of Typhon becoming trapped inside Etna; it's interesting how different cultures come up with similar legends to explain their volcanoes, however I am sure there are many reasons for this which classical scholars could explain to me.
The island was formed by the activity of three volcanoes going through four stages of eruption which resulted in Teide's current caldera. This is thought to be formed by either the vertical collapse of the volcano or a series of lateral gravitational collapses. There have been many historical eruptions of Teide, one is thought to have been witnessed by Colombus as he sailed to the new world. Teide remains an important symbol to Tenerife and is on their coat of arms (I have written about volcano flags before so it's good to know that there are some). Finally I would like to dedicate this post to my friend Ian Teader whose name is a bit like Teide.