In deep water crossings there are two major factors to be concerned by.
1) Debris. Debris can be sharp, long and perfectly aimed to fit through the grille and punch a hole through your intercooler, airconditioning condenser and radiator in one swift movement, rapidly introducing water into the engine's intake manifold while ruining the air conditioning and radiator at the same time. A wading bra (or substitute) made from either rip-stop, canvas or other tough material combined with moderation in entry will protect you.
2) Radiator fan propulsion. The radiator fan is exactly that - a fan. It draws air from in front of the car through the radiator. Since water is 680 times denser than air, it stands to reason that the same fan moving at the same speed but now immersed in water will exert MORE force on the water than it would on the air. This force has to be balanced (Newtons laws) so the fan will try and dig its way through your radiator. The trick here is to form a steady bow wave and keep it going, and DON'T EVER rev the engine hard. Light, moderate, constant RPM and preferably with a wading bra in deeper water and you'll be fine.