Can a creature fly underwater? I’ve never heard of a
normal bird flying underwater. What are the rules
regarding this? If it’s possible, what is the penalty to
movement and maneuverability?
Flying creatures must swim when they enter the water, just
as other creatures do. A fly spell lets you swim at your normal
flying speed, but with the same maneuverability as other
swimmers (perfect maneuverability). Incorporeal creatures also
can fly/swim in this manner (they move through water just as
easily as they move through other substances). Note that
gaseous creatures cannot enter water.