http://skyrim.nexusmods.com/mods/21889
Ever stood on top of a boiling geyser in real life? Well, you can in Skyrim - hence the need for this mod.
This is a simple mod which makes volcanic water (such as the hot springs outside the Eldergleam Sanctuary) do 2 points of damage. Just enough to dissuade you from staying in it for too long.
Most areas that have geysers (technically "perpetual spouters") are affected, but one or two sections of water that look volcanic aren't recognised by the game as volcanic water and won't cause the damage.
An unintended side effect of having the water cause damage is that it appears to kill the bathing hunters nearby if you're in the area for long enough. Serves them right for trying to bathe in boiling water.