>To fin along a path less trodden is part of the attraction, but there are many other reasons divers explore caves. With no sunlight to sustain bacteria and no water movement to hold silt in suspension, visibility can reach astonishing distances — up to 200 feet in some caves. In an enormous chamber, divers may be able to see another tiny pair of divers and their lights all the way over on the other side, the water so clear it is literally invisible — like floating in space.
>Some caves actually look like the surface of the moon, with pale white limestone carved into strange, unearthly shapes. In other caves the water moves along rapidly, and divers swim against the flow going into the cave and, if the passages are large enough, fly along with the flow heading out. Dives like these are truly remarkable experiences. On the other side of the coin, sometimes the water flows inward from the entrance, and divers need to be extra cautious to turn around with enough remaining gas to swim against the flow and still make it out with gas in reserve for safety.
>To the trained eye, caves offer as much variety as exists between different shipwrecks or different reefs. Some caves have white walls, some dark walls that eat your torchlight, and some have stripes from alternating seasons that either send dark water into the cave or clean water to flush it out. Because they are most commonly made of limestone, many caves have beautiful fossils embedded in the walls.
>Strange animals live in caves. Having adapted to the cave environment over eons, they may lack pigmentation and appear pale white; many are blind with extra-long feelers to detect food in the complete dark.
>In the same way ocean divers often develop a store of knowledge over time, so too do cave divers, and conversations leading up to and following dives are as animated as those on any dive boat. In short, cave diving offers an opportunity to visit unique environments with adventure aplenty and as part of a dive group that shares a passion.
>After the cavern diver course, we usually go dive caverns as much as we can until we start shining our torches around the bend and thinking, "I wonder what's down that passage." The next level of training is usually an intermediate phase in which divers start diving with more than one cylinder and practice running line. Several types of reels are available today, and divers should learn to use the ones they will be using after the course. Some caves have a "gold line" from the entrance through the main passage; some require the lead diver to lay line beginning some distance beyond the entrance to prevent curious novices from following the gold line into the cave. This training level usually comes with some restrictions so we don't go too fast too soon: "no leaving the main line to explore side passages" or a gas restriction such as "no diving beyond a third of a pair of doubles," for example. Different training agencies have different restrictions, but they are all intended to encourage new cave divers to gain experience before moving even farther into the earth.
>After making a number of cave dives, which seem incredibly adventurous, you'll be ready for a course to become a "full-cave diver." This level of training includes learning to dive complex caves, running short lines (called "jumps") and using line markers such as arrows and "cookies" to record information such as who is still in the cave and which is the shortest way out. Each level of diving increases the amount of potential anxiety divers may experience, so they should gradually add to their experience before progressing. There are a few other pathways to cave diver (in the U.K., for example, divers serve an apprenticeship), but the principles listed here hold firm regardless of the agency by which a diver is trained.
>With that training comes the expectation of suitable gear, and such gear usually costs a bit more than the equipment used for ocean diving. Many of us have been diving for years before we get into the darker side of diving, as cave diving is affectionately known. Considering the experience, the cost of the gear and the expense of the additional training, today's cave diver may be a few years more seasoned and a bit more cautious. In general, we also have high-quality, well-maintained gear and, above all, advanced training.
>One of the added benefits of getting trained as a cave diver is that the skills developed along the way carry over into the rest of our diving. Many of us change the way we fin even when diving reefs so we don't throw pressure waves down onto the wildlife. We feel more comfortable carrying an extra cylinder and regulator when making deeper dives, and our gas consumption tends to drop as we improve our trim and buoyancy control. This means we use less gas on average, so our dives become less physiologically demanding.
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>© Alert Diver — Summer 2012