I also got stranded on water in my windsurfing days. It can be much more scary, death becomes a feasible outcome.

On the bike nothing much .. a couple 5+ mile walks, calling for pick-up a couple times, etc. It's sooooo much more pleasant when there is dry land everywhere!

I do carry plenty of stuff when on longer rides for tire repairs.. tube, pump, patch kit, tire boot, Stans darts and Dyna-plugs. Plus a multi-tool with a chain breaker. I don't bother with CO2: shoot your wad and you are toast.