Drowning

From Wikihack

Drowning is a means of instantaneous death caused by being submerged in water when you do not have either unbreathing or amphibiousness.

Common forms of drowning are:

• Stepping or falling into water when you have too much encumbrance to escape.
• Falling into water with no adjacent, non-occupied land tile to escape to.
• Being pulled under water by a monster's drowning attack.

If you can teleport, you will attempt to teleport away with a certain probability (before crawling out), provided you have sufficient energy. If you also have teleport control, you always will attempt to.

As a side note, if you have teleporitis, random teleports will never place you in water only if you are neither unbreathing nor amphibious.