Word of caution: Pay attention to the clock when you're pre-swimming!

After completing my first pool-swim sprint triathlon many years back i decided to sign up for an Olympic distance with an open-water swim. It was a beach start with about 250 people.

Prior to the race I read lots about the open water swim and learned that the best way to stay calm to avoid panic is to get in the water ahead of time and swim around. On race day i joined many others and day i did just that. The water was cold but after swimming for a while in the wetsuit i started to warm up, the sun was shining and getting warm and i remember really enjoying it and feeling confident...until i noticed i hadn't seen anyone else in the water for a little while. My goggles had fogged up and as I took them off and stood up in waste deep water about 30 feet from the beach to look around to see what was up i heard the air horn and saw 250 people racing towards me jumping and diving into the water. I put my goggles back on and started swimming but not being the greatest swimmer i probably had about 150 people swim on top of me for about 5 minutes. It was a pure washing machine with lots of gasping for air. I ended up surviving and enjoyed the entire race, but wow, really rookie mistake.