Bromine Lake is a special lake. Its size is huge. It is the size of a small insland sea. Such one would think such a lake, fed by mountain run off, would be extremely cold. Such is not the case. Even in the dead of winter, the water is nearly the temperature of a living human (99F or 37C). The water is not sulferous or with any odd scents or smells like most hot springs. It is clear and blue (as the conditions make normal growth minimal - being too warm), with a faint glow in the dark of the night.
The warmth of the water keeps the valley moist and warm as well. While this makes molds a problem, it is a boon for the surrounding farmers. Even in the deep winter, when it snows, the snow soon melts near the lake. This allows for more rounds of crops than anywhere else in the known world. The villages on the shore do some fishing, but mostly they ferry people and good across the lake. (The lake has few fish, as none of the local species seem adapted to it). The fertility and somewhat central location of the valley and lake has made this piece of real estate hotly contested by the three nearby countries.
There are hundreds of theories on why the Lake is this way. It does not test for magic. It is not a clerical nexus. It is not a curse. While the lake is a stop on the Draconic Migrations, they are not the cause. When asked, the Dragons only stop because it is warm. They do not know the reason why.
The reason is simple, but no one knows of it. It ties to the Legend of Corvus. After the Voop, one of the great elemental orbs fell into the lake. These are orbs of such great power that even Corvus could not control them. The Flame Orb sank into the lake, deep into the muck. In an attempt to free itself, it tries to boil off the Lake above it. Without air, there can be no flame. Without flame, the orb can only generate a “little heat” in comparison. Given the constant inflow of water from the rivers and its sheer size, the orb only heats the lake. Also the agitation of its heating only serves to push it deeper and deeper into the silt and much at the bottom of the lake.
The elemental orbs were not very bright in comparison to their other orb relatives. But what they don’t have in brains they make up in raw power. Should this orb ever be freed, without Corvus to stop it, it could literally burn everything off the surface of the world.