For mines in the UK up to waist depth water I usually have a furry suit and then an oversuit, one of the warmbac cordura ones or the meander PVC yellows ones. The PVC ones tends to be better I feel due to it being PVC and not PU backed like the warmbac one (which tends to leak after a while, also a ****** to clean as mud gets worked into the material).
For long waist water depth trips or deep water I will put on a 3mm wetsuit, which is fine for water found in mines as it is still, running water like in caves is a different matter as it is colder, so a thicker wetsuit is needed.
All stuff available from Bernies, Inglesports, Warmbac direct, Caving supplies.
I have had my warmbac cordura suit since summer 2004, approx 2 trips a month since then, suit material is good, no rips, but the PU waterproof film on the inside leaks now. Others use the Meander PVC suit and seem to get a similar life, but without the leaks.
Mr Mike www.mineexplorer.org.uk