Any 4wd enthusiast worth his salt will tell you that the main reason for fitting a snorkel is not to increase wading depth. It is to raise the air intake to somewhere where there is cooler cleaner air. As opposed to the inside of the wheel well that is very hot and dusty. This leads to a longer life of the air cleaner and ultimately the engine. As a secondary it also increases the wading depth (but there are other things that need attention as well). And thirdly it looks very cool.
We bought a Safari Snorkel. Good quality item with all the necessary hardware to fit it. However you will need a stepped drill bit and a big hole saw. I think they recommend 92mm but you can buy a few mm smaller, as long as you measure accurately. If like us this is one of the first mods you do, be warned. Drilling a massive hole in the side of a perfectly working car is harder than you might imagine. All in all an easy job. Just make sure to paint over the edges of where you drilled through the paint to stop rust. Remember rust never sleeps.