fawk me, some serious BS in this thread.
run your breathers as high as you can, into cabin, into air box etc. guys, these things have one way valves on them. water comes in and the cap seals, if in doubt then run a proper one way valve.
as the diff, t/case cools it WILL pull water past the seals in the axles add to that the pressure of the water against the outside of the seal (designed to keep the fluids IN the axle not out) and presto, water comes in.
then you have the manual tranny which doesn't have a vent line so water enters through the shifter tower, nothing you can do there.
don't touch the clutch? are you serious? come on, really serious? so if you go in and find your hood disappearing in a deep hole, you just keep driving cause you can't shift into reverse to back out? seriously? BS.
the only time you REALLY need to worry is if you get stopped in water deeper than your diffs.
okay, so you want to take your pretty HZJ77 into hood deep water, screw that, lets go half way up your windshield. what do you do? first, walk the water hole. how deep is it? if it is shoulder deep then WTF are you doing, find a way around or turn back ... unless of course you are in Alaska where you don't have a choice. hip deep? smooth bottom or rough, loose gravel? mud? sand? buried logs? make sure you know what is under the water BEFORE entering it, there is more to water crossing than what MIGHT make it into your housings.
water is no big issue. silt is nasty s*** and needs to be cleaned out immediately after returning home. it screws with brakes, bearings and seals. grass is a very close second, it gets wrapped around the driveshafts and tears out seals and even ujoints. nasty s*** there.
steady momentum is best over rough terrain in water.
smooth bottom? open it up, tons of fun.
don't be scared to reverse out of a hole or to change gears while in water.
the big no-no is to sit in the water with your foot on the clutch, water can get in between and then, well, your stuck but to just shift? no biggie at all.
hell, if you want to do some research there are guys that pressurize their diffs and starter and t/case to keep water out. i guess if you are in Florida where they have their swamp buggy races this is good advice.
most important, once you suspect you have water contamination, when you get home then pop the fill plug and see how much diff fluid comes out. that will tell you how much water you have in the diff. if you get a liter of oil coming out then you have a liter of water under the oil and it is time to change it out.
starters don't like water
alternators don't like water
bearings don't like water
seals couldn't care less
electrics don't like water
most of all, your engine will nto be happy if you suck water in, nor will your turbo.
drive smart and you won't have an issue. be stupid and pull out your wallet.