Player's swimming skill may increase randomly when running around Lavastorm.
 

Steps to reproduce:

1. Head to Lavastorm, go to the flat area close the entrance by Ruathey (-1521.76 295.71 14.27)
2. Run around the area for a considerable amount of time (may be related to player race, I encountered this as a Dwarf).
3. Observe that you gain skill points in swimming despite not being in water.

This happens in a few places, where your feet are just above water - the ice river in Everfrost, and the "weird water" in the Erudin bay as well.

Most likely your feet are just above the lava, even tho you are on ground, and the same effect is taking place.