Axle Breathers etc

Several places sell extended breather kits.  Have a look on ebay or search on google for suppliers.  There is one on each diff that will probably require replacing if not extending (mine were in terrible condition) as well as on on both the gearbox and transfer box.  You will probably also need a wading plug for the timing belt casing.  It is important that you do fit these extanded breathers if you wish to venture into deeper water.  The diffs for example are known to suck in water especially when warm and plunged into cold water.  If you breathers are underwater, the water added to your oil will greatly increase wear to the diff and cv joints etc.  If you breather is blocked, the water will find a way in.  This usually means one or more seals will be destroyed.   

Extras

If you have the time/money/inclination then removing the original land rover viscous fan and replacing with an electric one helps.  The standard fan doesn't half throw mud and water all over the engine bay!  Also remember not to go in the water with your lights on, your asking for popped bulbs at best!