I rode through a flooded section on my work commute several days in a row. Water was over the BB and wheel bearings. It took about 2 minutes to get through. I rode past cars that were stalled out with drivers still in them. At one point I actually saw a fish swimming past my front wheel!
Upon seeing it the first day, I stopped before entering and considered my options. Re-routing to avoid meant being late for work. So I removed my shoes and socks and strapped them to my rear rack. Once I was through, I shook the excess water off my feet and put them back on.
The bearings showed no problems for thousands of miles after that, although I did have to clean and lube the freewheel. Those have no seals.