Always wear proper footwear while on or around a boat. Boat shoes, sneakers, closed shoes of any kind are the way to go. Believe me, I speak from experience. After lecturing everyone on board about the need for appropriate footwear, I foolishly wore open toe sandals during a long cruise. I neglected to change them when we pulled into dock and, while tieing up, I slammed my foot into a large dock cleat. Knocked off balance, I stumbled forward, heading toward the water, and nearly fell between the dock and the boat. Instead, I over corrected and fell onto my back hitting my head on the dock. I suffered a mild concussion and a badly broken toe.
As I always say, if you can't be a good example, be a really good cautionary tale.