Water 'shield'

if you ever played sonic 3 or sonic and knuckles, your favorite shield was probably the Water shield, which surrounded sonic with a bubble that allowed him to stay underwater without drowning and gave him a bounce attack. But I always thought it was wierd, i mean, its a BUBBLE! a simple bubble, yet it deflect bullets and other weapons fire. Don't worry about Sonic, Link won't just let him drown.