I suggest don't drive through floods unless you really have to and if so drive at a slow even speed so as to minimise the risk of water being forced into the engine bay, etc. Take great car when driving an automatic as there is likley damage to its gearbox electronics. Cars are wonderful things but submarines they ain't.
True, there were floods too here and people complain the least about electronics. One can cause major damage to engine if it sucks water inside the engine block, the kind of damage you get from a broken cam belt.
I'd just add - never drive into flood where the water level in higher than your air intake, and if you did and car stalled, do not turn the ignition on. Call for tow, get it to dry area, take off the plugs, turn the ignition on so that pistons go up and down a few times, put the spark plugs on again and only then try to start the engine.
That's for petrol. Diesel is much riskier in such situations.
You have to check and possibly change
(both engine and gearbox) if you have mixed them with water - when heated the combination of water and
is not the least healthy for your vehicle.