A wetsuit is a tricky bit of dive equipment to buy - as everyone only wants to buy one. Realistically though if you are a travelling diver in an ideal world you would need at least three different thickness of wetuits to cater for global water temperatures. But in the real world and due to us all having limited budgets, our usual recommendation is that if it is to be just one wetsuit then it should be a 5mm wetsuit - a 5mm wetsuit is the most versatile and will cover the widest range of diving and snorkelling temperatures. Diving in the Red Sea, Meditterranean summer diving and perhaps even mid Summer in the UK with a 5mm shortie overvest or hooded chickenvest. Whereas a 3mm wetsuit will usually cover you for Caribbean, Red Sea in summer, Indonesia and Thailand. Then for the chillier dives either a 7mm wetsuit or semi-dry wetsuit for the UK.