Funny, the only time I drowned my TW was in the Desert! Crossed a steam of unknown depth(I know) and got up to the tank in water. After dragging the bike to dry land and sitting in the Utah sun for 15 minutes, it started right up and we continued on our way. After 5000 miles the bike just keeps getting better!
As I side note, when a lot younger and crazier, my friend rode his TS 185 into a lake. We pulled it out and removed the head of that little two stroke with the bike's tool kit, pumped the water out of it, reassembled and rode off. He swears the bike ran better after that!
Not sure if I have a point to make with these stories but drowning an engine is not necessarily a death sentance.