While gliding into water or lava, player continues gliding

The bug

While gliding into a body of water or lava, your player continues to glide instead of swim.

This means you can still use fireworks in order to accelerate and get out of the water or lava.
It also means that when you reach the surface of the water, it is impossible to get the player model back in upright position until you touch the surface of a block.

Code analysis by Oval here.