The last thing you want is to walk away with a $3,000 suit you'll never use or a membrane suit that will leave you trapped underwater and freezing.

Wet suits are great for warmer water dives because the neoprene material allows water in and traps it against the body, which then heats up to your temperature and insulates the body. The general rule of thumb for wet suits is: the tighter the fit, the better.

Otherwise water will just keep entering and exiting the suit, without time to heat up against your body. You can choose from 2 - 9mm thicknesses and from shorts or full-length styles.

Shipwreck or cave divers are best off purchasing full-length diving suits with toughtex neoprene, which provides an extra layer that's snag-proof. You'll want your suit to hold up in the tightest squeezes and off the sharpest coral.

However, for diving in water less than 60 degrees Fahrenheit, dry suits are the only sensible choice.

Dry suits can be made out of several different kinds of material: neoprene, membrane or a hybrid of the two. Neoprene is made out of synthetic rubber and is the most rigid type of suit and though difficult to get on, will keep you the warmest.

Another advantage to neoprene is that it's less susceptible to rips or tears and will maintain functionality and buoyancy if a rip were to occur, making it perfect for those cold water wreck or cave diving expeditions.

Membrane shelled suits are generally the most comfortable -- made of thinner nylon or vulcanized rubber material, waterproof and breathable -- and are recommended for divers who will spend a lot of time out of the water on the boat.

Because the material is thinner, divers will need to wear an under layer made of polyester or another tight-fitting material. The latest models are hybrids with a rigid, overall-style neoprene bottom that supports proper kicking and a looser-fitting membrane top to allow easy arm maneuverability.

Your local scuba dive shop will be able to assist you in purchasing dry suits. If you're shocked at the $1500 - $3000 price tag and don't foresee yourself ever diving enough to warrant that kind of investment, then you'll be happy to know most places will rent them to you for around $40-$50 per day.

Sometimes you can even find weekly specials or package deals at popular scuba diving vacation destinations.