Warm-water divers may use full-foot fins and not even think of dive boots. However, if you dive in cold water, dive boots are a vital part of your gear. They help keep your feet warm and safe in many conditions and help prevent hypothermia and other dangerous conditions. When choosing diving boots, look for:
1) Warmth. With the exception of dry-suit boots, most dive boots allow some water to enter your boot. The water becomes trapped and becomes warmed with your body heat, which in turn keeps you warm. Besides this feature, there are many factors that can influence the warmth of your boots. For example, most dive boots are made from a material known as neoprene, which is measured in different millimeters. As one might suspect, the higher the number, the thicker the material and therefore the warmer the boot. For most colder water dives, you will need boots at least 7mm thick. Fewer seams will also mean a warmer boot and fewer leaks, so this is a feature you might want to look for.
2) Closure. Dive boots can include a zipper, can be slip-on, or can use a Velcro strap or tab. Zippers make putting your boots on quite simple, but can make your boots less warm. Straps and tabs allow you to adjust the fit of your boot but can keep you warmer.
3) Comfort and fit. Poorly fitted boots are a distraction on a dive and can hamper your movement under water. Boots that are too loose can partly slip off your foot, creating a hazard. Large boots can also prevent water from becoming trapped near your skin, which means your feet will be very cold during your entire dive. Boots that are too small will pinch and hurt your feet. They will also likely cause leaks as the seams strain.
4) Durability and protection. If you are diving in warm waters, you might want booties, which are more like socks than boots. Booties do not add warmth, but they do protect your feet from raw spots, blisters, and other problems, which can arise even if you wear full-foot fins. In warm waters, any irritation on your foot can mean infection, so boots are vital. If you are diving in cold waters, look for boots with a reinforced sole. Since most dive boots are made with neoprene, which is not very durable, many dive boot manufacturers reinforce the sole with another material. This helps makes the boots more durable and slip-resistant as well. It also pays to look for thick soles on your dive boots, as these will protect you from sharp rocks, broken glass, barnacles, and other dangers your feet may face both in and out of the water.