Living on the coast of North Carolina, in one of the best dive sites in the world (so say the readers of Rodales year after year) and an active and experienced diver, I have a few comments.<br><br>First and foremost, a companion that dives with you may be a friend or buddy, but the only person that you can rely on in an emergency is yourself. PERIOD. The most important thing to do is to have redundent systems for doing anything critical, such as breathing, ascending safely, and keeping track of your dive profile.<br><br>I never dive without a pony bottle (30 cu ft), a lift bag, wreck reel, two knives, a second computer, whistle, a mk 13 mod o flare, and a set of dive tables .<br><br>All of my diving is in water greater than 80 feet in the open ocean from a boat. The pony is an alternate air source that will get me back to the anchor line and the surface without a concern.<br><br>The wreck reel and lift bag will get me back to the surface, allowing me to do a decompression or safety stop, tethered to the bottom without drifting far from the boat and safety.<br><br>Two knives are important. Unlike Mike Nelson, I have yet to be in an underwater knife fight. In fact, I have only used my knife for cutting once underwater. I use a leg mounted knife for prying "things" loose. I have a second small and sharp knife mounted on my chest strap for real cutting and entanglement.<br><br>I never get in the water without a backup method of keeping track of the dive time and depth and any decompression penalty that I may accumulate.<br><br>For suface signalling, I keep a "sausage" and a whistle on my BC Vest. <br><br>In my opinion, a leatherman type tool is not appropriate, as they will rust solid. Also, NEVER put a "suicide clip" on anything.<br><br>Just some observations after investigating a dozen diving fatalities and treating about 100 divers with DCS.<br><br>Obviously, for a quarry, lake, or shore diver, the requirements will be different