It doesn't matter. The results are the same. The world goes dark. The river the word hardly does justice to the churning mess enveloping you the river tumbles you like so much laundry. It punches the air from your lungs.
Swimming is a joke.
You know for a fact that you are drowning. For the first time you understand the strength of the insouciant monster that has swallowed you. And another hundred feet just short of a truly fearsome plunge, one that will surely kill you before you see the rescue lines. You're hauled to shore wearing a sheepish grin and a look in your eye that is equal parts confusion, respect and raw fear. That is River Lesson Number One.