Man &d, glad you got out ok, that sounds bad. Honestly though, are you not fessing up to zipping up the suit all the way or something? I don't see how that much water could get in your suit without it being obvious what happened. I just got a drysuit this year and made the rookie mistake of leaving the relief zipper open during a run - scared me straight.
I've had one swim on Canyon Creek in Washington. It was on the Big Kahuna, the main waterfall on the run. Apparently I didn't know what I was doing (what do I know about waterfalls...) because I thought I was on line, but when I hit the bottom I did a monster stern squirt out of the water, my boat caught air and I flipped over backwards, rolled right up, but the water was pushing hard into a slightly undercut wall on the river right. Before I could paddle away, I hit the wall, flipped, and then rolled up again against the wall. I thought I'd made it as I put my arm against the cliff wall to brace myself, but got flipped again, tried to roll but got rejected under the undercut and think I swallowed a bit a of water on that failed roll. Tried to set up again, but was getting nothing but wall. I'm sure a better man would have hung in there, but given that I knew I was in a giant pool, I pulled and swam my stuff to shore.