The Elemental of Chilshire Deeps

On the eastern end of Eishin is a vast lake known as Chilshire Deeps. It is named for one of the two towns along its western shore, each in a small pocket of arable lands nestled between tall snowy mountains and the large lake. A sizeable portion of the lake's surface remains frozen solid year-round as one would expect on this frigid continent, but a quarter of central western side of the lake has no ice and the waters, while still cool, are far warmer than one would expect for the climate.
Scholars claim that the lake bed has several vents that spew a hot gas into the lake which causes that portion not to freeze and to stay temperate. The hot springs on the western side of the continent are certainly good evidence to support that theory. But locals being what they are, especially in far flung locales that attract few outsiders, have a far more fanciful theory which is far more popular and the only one that anyone there will tell you.
The local mythology says that long ago, a powerful fire elemental named Duke Ragnis who was imprisoned in Dalaein was able to escape and elude capture. The elemental was supposed to have fled to the most unlikely place for one of his ilk, and gone to the frigid continent of Eishin and submerged itself in the waters of the lake that has become known as Chilshire Deeps. The elementals presence was hidden from its pursuers, save for the vast swath of lake that no longer freezes over. The locals claim that each year they light a massive bonfire on the edge of the lake to honor Ragnis for giving them the gift of the temperate waters. Purportedly the fire always burns for more than a week despite them not adding wood or tending it in any way. The townsfolk believe that Ragnis comes to the surface each night and uses his powers to ensure the fire will continue to burn and to give his thanks to the people for not turning him in to his jailers.