Wetsuits are a great way to keep you warm in cold waters while diving. A wetsuit works by allowing a thin layer of water to penetrate the suit for insulation. The layer of water between your skin and the suit becomes warm due to body heat and allows you to comfortably swim in cold waters. With diving, you'll experience drops in temperature as you swim to different depths so keeping warm is a major priority.
In addition to keeping you warm, you can customize your wetsuit to fit your every need. They come in an array of cuts, thickness levels, stitching, and zipper styles. The thickness level of a dive wetsuit will dictate how warm it'll keep you. For example, a 3 mm wetsuit will keep you warmer than a 2 mm one. You should choose a thickness level that's suitable for the water temperatures you'll be diving in.
Furthermore, make sure the wetsuit you use is for diving. Although triathlon and surf wetsuits are very similar, a dive wetsuit will focus less on buoyancy and more on the level of insulation. Buoyancy is a lesser issue when it comes to diving since you'll be using weights to control your buoyancy. Dive wetsuits tend to be made from a more durable blend of neoprene as well. These wetsuits need to be extra durable to combat the heavy, bulky equipment that will be layered on before a dive. With these facts in mind, you'll have a blast diving when you sport the right dive wetsuit.