I'm incredibly afraid of swimming in a body of water of which I cannot see the bottom. It's incredibly ironic considering I do it at least once a day (or night) in the summers in TN. I think that I'm mostly afraid of anything biting me or touching my feet in general. I picture animals such as crawdads, really big carp, snapping turtles, alligators and sometimes squid reaching out to grab my ever-so-delicious-looking appendages. I'm also pretty sure that a monster similar to that of Loch Ness surely lives in the Res, it's just that no one's ever sited it yet.
One of these days, when I go lap swimming alone in the Res or Lake Dimmick and I don't come back, you'll know that I didn't drown; I'm a distance freestyler for Christ's sake. Some giant monster came and devoured me. At least I don't let it get to me too much. Although I do tread water horizontally, which my friends probably find a bit odd.