The term you're looking for is Wading Depth which is specified by the manufacturer. They may surprise you, and its info you should know about your vehicle. Its in your manual, or search it online.
- Jeeps say 500mm, and some models go to 700mm
- Mercedes GLC SUV has a wading depth of just 300mm
- Landrover Discovery (not the more compact Discovery Sport) has a wading depth of 900mm - this is the depth where the rear starts to float.
- A Nissan Leaf has a colossal 700mm maximum wading depth - yes an electric car.
- A Nissan Fairlady has an air intake behind the headlights, so its only able to go around 2 inches of water, and that assumes flat still water.
The safest assumption for any car is DON'T drive through water. Next is "no deeper than the sills on the car. For a car-based SUV its no more than a car. For a proper 4WD then "center of the wheel's axle" is a safe minimum. All this assumes an unmodified vehicle.
Discussing the two videos:
The first shows a pair of relatively unmodified utes (pickup trucks) attempting to drive upstream against water flow. They are not in the center of the river, so are likely on a slightly shallower ledge.
The vehicle nearest camera is stuck because its traction is equal to the pressure of the oncoming water, which is why it can't make headway. The passengers are bouncing to try and increase the traction.
The Isuzu DMAX ute has a fresh air intake right over the wheel arch nearest the camera. Its more at risk from flooding the alternator, which is slightly lower.
These two vehicles are at about their maximum depth for water crossing.
RISKS: Thankfully they're playing in the shallows - the end of the recording shows a small protrusion upstream, shielding them from the worst of the river's flow. Had they tried to cross the river at this ford, it would have ended up with vehicles floating downstream out of control. Notice the nearer vehicle gets out by moving right, into a shallower area and then gets traction. The further vehicle ends up being pushed backward by the river flow. And there's a lot of water released out the driver's door at the end.
The second shows a modified Australian Toyota series 80 crossing a ford that is really a too deep for a safe crossing. The vehicle floats because the ground has dropped too far below the water surface. This causes a loss of traction, and the slow current pushes the vehicle downstream. This is a bad situation and now the driver has no control. Fortunately the river bed got slightly shallower near the edge, the speed of the water current slowed, and the front wheels got enough traction to overcome the current. Now driver has regained some control and can edge into the shallower area, and get out.
RISKS: vehicle risked being washed downstream out of control, and possibly snagging and turning over. This was incredibly dangerous, even though it was relatively calm. Ideally they would have roped up to the rear towhook so that it could have been pulled back out once floating, but once traction is lost then its gone from planning to reacting
Another possibility would have been to allow the vehicle to fill with water, decreasing its floatation, and letting it get traction. Risk here is that you're sinking and may drown yourself. Plus all the stuff inside is going to get wet (which happens anyway, notice the driver's door at the end)
In the still-image above, notice the large black plastic air intake on the A pillar, sweeping down into the driver's side wing? This is an air snorkel, and the engine breathes in here. Its the motor equivalent of
When the snorkel/schnorkel's end goes underwater, the engine will draw water in with the air, and will suffocate and stop, potentially causing expensive internal damage. You don't want that.
It doesn't have to be water either - enough spray or rain or mist can cause issues for the engine too.
There is no need for an exhaust snorkel - the gasses will force the water out the tailpipe and bubble up, as long as the engine is still running. Some dual tailpipe exhausts have issues if there's a common chamber, where one side floods and the other side keeps venting.
If the engine stops in water, you're pretty screwed. Best practice if the water is over the axle/wheel hub is to be towed out and then restart motor. But you may be blocking the path out. Time is also critical, the longer you sit in water the deeper your wheels will sink in, and the more water ends up in the cabin. Plus allows more time for water to get into your electrics.
Here's another snorkel, showing how it connects to the air filter/airbox. I have personally driven this through water that was over the bonnet (hood). Fortunately it was compacted shingle so a good firm footing. Had it been mud or silt or loose shingle, then that would be much riskier.