I think that's been changed now, by the way

Also works great in dungeons that are not underwater.  Your channeling is based off your exact coordinates when you start the spell compared to where you finish, with a chance to channel more the closer the numbers are.  You can even cast a spell, run around, and get back to where you started before it finishes to channel.

Back yourself into a corner. Pretty much the only way to channel while swimming.

Is there anyway to manage pushback while underwater? Even while levitating if im being struck underwater I have to pray for enough misses to get a cast off.

Underwater pushback