We did a lot of that in my family, back before the yahoos ruined crown land off-road sight seeing for everyone. Rivers are the most dangerous moments, without a doubt. I’ve flooded my ignition halfway across a rager that was up to the doors. Stood there for an hour waiting for it to dry to make sure it would start and I didn’t kill the battery trying to restart it hundreds of miles from town (and this was before cellphones). When I got home I got to spend a few hours changing the oil in all the gearboxes because when the differentials and transfer case sit too long in the water, they cool off and the vacuum created by that pulls water into the vent tubes, ruining the oil. I’ve sliced up tires on sharp rocks on the bottom that you couldn’t see, etc. Our worst moment was getting too deep in my dad’s Blazer. The water was up to the windows and at that point the current starts to push you downstream. We opened the doors to let the water run through the truck which gave us our footing back and we made it over. We slept cold and wet that night, I can tell you.
Picking the route is crucial. My dad taught me to read the currents, because the currents map the bottom for you. Most important is learning to spot holes, because it’s all over if you drop a wheel 18” down into a hole halfway across. Much like crossing on horseback or on foot, picking the widest part is most of the work (wide = shallow) and don’t ever, ever stuff your hood into something you can’t see the bottom of.
Honestly, climate change is going to make these old skills useful again. Every time I see footage of city slickers driving their cars through flooded streets, I wish I could go out there and teach them the right way to do it.
I’m constantly amazed by the stuff we did in my youth that I would never have the guts to attempt today. 
