They are air intakes (breathing in) not exhausts (breathing out) and are a common feature on the vehicles of those who like to pretend they know how to traverse deep water. I say 'pretend' for the following reasons:

1. On a modern Landcruiser or Landrover equivalent the standard air intake in positioned quite high up in the engine compartment. However, the safe water depth is way below that height. This is because once the water gets to about the top of the tyres, the pressure forces it past the door seals and into the cabin. There it finds lots of nice electronics to short out and disable the vehicle. An ancient Landrover or Cruiser is much more able to deal with this.

2. No proper driver would drive through a water hazard more than 30 cms he or a passenger hadn't walked through first to check for concealed rocks, holes, whatever and check the exit. Even if there are no electronics in a sodden cabin to worry about, for the snorkel to come into play it means wading through at more than waste-level, dealing with the currents, etc. and watching for crocs. It doesn't happen unless you're Kingsley Holgate and have half a barrel of Captain Morgans inside you!

So it's bling.