My friend dropped his fin gearing up in 45ft of water. Instead of swimming down the anchor line as we normally do, we dropped straight down and were able to spot it on the way to the bottom. He put it on and off we went.
Another time shore diving the swells came up fast and we got worked getting out of the water. My dive buddy lost her fin, and mask, well she also pushed my mask right off my face too. I tried to wade out into the pounding surf to recover the gear, but in a drysuit I wasn't comfortable with the risk of being knocked off my feet especially since I was already tired. Lost all of it...oh well, we suffered no injuries other than pride.
NEVER consider a piece of gear so important that unnecessary risks are taken to recover it. Often times on popular dives sites things will be picked up soon enough by fellow divers, and hopefully returned to the rightful owner. Which is a good reason to mark your gear.