First of all, avoid going into water that is deeper than exhaust, 95% of the times its better to wait than be sorry;
- Rickshaws and motorcylcles move with the sloshy water, so might bump into you.
- Horns are in-audible in rain, so you might hit/get hit.
- If compartment sealing isn't good, or if your car has an issue and have to open the door, you'll be having a hard time drying your interior + smell
- Water through the intake and you're done, you'll have to re-do your weekly plan and monthly budget.
- Your electrics would be tested and there is a huge chance they'll get an F grade.
If you still have to go, and you've got a back-up car following you, look for where the other cars are going easily.
Exhaust under water IMO isn't an issue, water head above exhasut outlet would surely create back pressure but that can be overcome by higher than usual revs. driving in reverse in water however, would push in water.
I once has an experience with 7th gen civic, for an instant water did cross from above the hood onto wind-screen, but somehow survived that, ... not doing that again.