Pyre Lake

This subarctic lake periodically releases flammable gases from its lake bottom, especially in late spring and summer when the permafrost thaws. A species of flying insects from another world has somehow found her way here and through some quirk of their internal chemistry manages to set the gases aflame. While the insects responsible for starting the blaze also die in it, the others dance nearby, as the flames are important for their mating process. The locals blame the fires on unquiet spirits instead, dubbing the location Pyre Lake for this reason.