When a goat goes into water or lava, instead of floating at the top, it sinks to the bottom like an undead mob.
MC-221695 Goats don't rise underwater
MC-221713 Goats Don't Float In Water
MC-222001 Baby goats sink in water
MC-222044 goats cannot swim
MC-222233 goats sink in water
MC-222381 Goats can't swim.