I am not sure what it is about Land Rovers and water. Most people with an interest in offroad driving get some pleasure from driving through deep water. Land rover provide a good high safe wading depth from standard but if you want to go beyond that there are a few things you will need to do. Obviously, if you go driving round in deep water, you make your own decisions and take your own chances - the following is just my personal opinion!
One thing that I do know is that you must prepare for deep water - if you don't it will cost you far more!
They look good, protect your egine from water and also from dust! They dont always have to be expensive. See my DIY series land rover snorkel page for a very cheap option!
Water and electricity don't mix. If you have a petrol land rover, this is a problem if you want to go wading. Mine does surprisingly well in the deep stuff with only a few simple steps. My distributor is covered with a rubber glove. The tips are chopped from all 5 fingers and a lead fed through each. This is a pain to do and doesn't last forever. I am yet to find a better way.
My coil is seated in a Tupperware box on the bulkhead, the leads are fed through holes sealed with silicone sealant. The plug ends of my leads are given a liberal coating of wd40 before i go near the water.