Beaching is a mechanic that can do in an aquatic creature. It sharply reduces comfort such that any player who has managed to beach themselves is in immediate peril of death if they do not get back into the water. Should a player become beached, their turn radius will become significantly reduced. They will also suffer from a greatly reduced movement speed. It will be very difficult to get back into the water if you manage to beach yourself high up on the shoreline. One of the easiest ways to become beached is due to receding tides, dropping water levels after a storm, or perhaps a nastily thirsty Apatosaurus who decided to drink your lake dry.
If you become beached, you are a very easy target for predators in a relatively helpless state.