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. This could be caused by a foocubus or nymph removing your boots of water walking, levitation, or Ring of levitation.
- Being pulled under water by a monster's drowning attack.
Less common forms of drowning include displacing a flying pet away from water onto the only dry land available:
If the dragon D is a pet flying over water, then displacing it will likely prove fatal for our hero, who has no place to step back onto dry land. The more pets there are, the more confusing the situation is, and the more dangerous. Do not try to navigate Juiblex's swamp with a swarm of pet bees.
This link describes the tale of a player who was blanking potions on the Castle level by repeatedly walking into the moat while holding junk potions, and who drowned because a giant threw a boulder at him. Since that resulted in the only dry land tile adjacent to the water to suddenly be occupied, YASD by drowning ensued.
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 will always attempt to do so. However, it will not work on a no-teleport level.