One of my most challenging rides was shortly after I started bike commuting and didn't know better. I was riding to my girlfriends house during a big rain storm, and was riding in a puddle that kept getting deeper and deeper. Eventually the water was over the bottom bracket with each pedalstoke making a splashing sound as my foot went under water as I realized the water was up over the top of the base of the supports for the high voltage power lines that the bike path runs under. I pedaled out of there as quick as I could and haven't repeated that mistake.