Nest of the Sea Serpent

The Crow's Nest covered in thick fog with a deep crater at its peaks has always been subject to many stories and legends. One of the more popular tales says it originally being a volcanic isle that was also home to a sea serpent that made a crater by swallowing it whole. Although the crater may appear useless and immeasurably barren, people sailing near Crow's Nest have occasionally reported sightings of dark smoke rising above the island peaks. Blackened rocks and half-grown grass litter the grounds to further fuel such stories. Who or what is lighting up these fires?