NAUI Master Scuba Diver 48 The Diving Environment (68°F) to thrive. Corals are generally found on shallow parts of continental shelves and around islands in tropical areas. The reefs themselves are built of the calcium carbonate remains of coral populations over time. Some of the environmental parameters that are problematic for coral reefs include sedimentation, unusually warm water, pollution, and freshwater runoff. Kelp forests grow on rocky bottoms in temperate water regions around the world. These three-dimensional communities offer a very diverse and productive environment for divers to explore. Large brown algae can form underwater forests and surface canopies, home to many species of algae, invertebrates, fishes, birds, and marine mammals. Special training is required for diving in dense kelp. Wetland areas such as salt marshes and estuaries are zones where freshwater, sometimes seasonal, mixes with ocean salt water. They are important as places of spawning and juvenile development for animal populations, and also act as filters for removing pollutants and sediments from runoff water. Sea grasses and mangroves help to support a rich and productive ecosystem of invertebrates and fishes. While not commonly dived by recreational divers, they are sites of scientific investigations which often utilize diving technology. Polar regions can offer exciting diving, but special training is required due to the extreme air and water temperatures, as well as the possibility of encountering ice. Also, blue water environments, which are essentially open ocean and far from shore, have a whole suite of organisms that may not usually be found near shore. Specialized techniques are necessary to keep divers tethered together, to avoid going too deep in this often disorienting diving environment. Many freshwater habitats exist around the world. Lakes, natural, and man-made are popular for recreational diving. While lacking the diverse species found in most marine habitats, they often offer unique experiences such as the chance to explore underwater structures or specific plant or animal species. Rivers can also be used as dive sites, but special care must be taken regarding currents and underwater obstructions. Florida is wellknown for its extensive network of freshwater springs, which can be warm and clear year-round. They are connected by underwater cave systems, which require highly specialized training for divers to explore. SPECIALIZED DIVING ACTIVITIES Divers engage in many specialized activities created by the environment. Natural formations such as caves, caverns, sink holes, and blue holes arouse our curiosity and interest. People dive beneath the ice, in mountain lakes at high elevations, in the blue waters of the open sea, and to depths in excess of 30 m (100 feet). All environmental diving activities have something in common: they all require specialized knowledge, equipment, and skills. Specialty training is required for any diving activity that is significantly different from that in which you have been trained. Special diving techniques to reduce the potential for environmental damage can be found later in this chapter. Man-made Structures Jetties, piers, and wharves can pose dangers from waves, currents, poor visibility, boats, and fishing lines and hooks. Submerged shipwrecks often attract divers, and some are extremely hazardous. Serious dangers include sharp objects, entanglement, entrapment, and getting lost. Special training and equipment are also essential for this type of diving. Offshore oil rigs can provide sites for excellent diving. Such rigs are located anywhere from just outside the surf line to over 300 km (200 miles) from shore in waters of depths that may exceed 90 m (300 ft). Spear fishing is often popular in these environments. In addition, the area under and around a rig is a virtual junkyard of cable, pipe, and other debris. Caution must be exercised to avoid entanglement or injury. Large underwater pipelines are common in some areas. Diving in the vicinity of active pipelines is discouraged because the lines may be discharging large amounts of pollutants that can cause illnesses. Pipelines may also include intakes that can suddenly suck a diver inside.
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