This article is a travel topic
Wreck diving is a specific type of scuba diving. Most wreck diving is done on shipwrecks, but wrecks of aircraft are also commonly explored by scuba divers. There are also a lesser number of more exotic wrecks which are dived upon, ranging from trains and buses to collapsed naval radar stations.
All scuba divers require some form of training, but many divers engage in additional training before diving on wrecks. Wreck diving is often subdivided into three types:
Non-penetration diving can usually be undertaken safely by most certified scuba divers. Divers are often recommended to undertake additional training, such as a wreck diver specialty course, before engaging in limited penetration diving. Full penetration diving is regarded as a type of technical diving, which requires significant additional experience, training and equipment.
Almost every scuba diving destination in the world offers some form of wreck diving. For many areas this is as an alternative to diving on coral and other reefs; in other areas, the wrecks are the only diving attraction.
Scuba diving publications frequently print articles about "the top 10 wreck dives in the world", and broadly speaking the 10 wrecks in any particular article tend to be drawn from the following list:
However there are a huge number of other very popular wreck dives elsewhere in the world, including:
Regional articles which include wreck diving sites:
Isolated wreck site articles:
In addition to basic scuba diving certification, many people intending to dive on wrecks seek further training, both for their own safety, and also to increase their enjoyment.
 Specialty courses
Many recreational diver training organisations offer wreck diving 'speciality' courses, as a supplement to basic training. According to statistics from PADI (the largest diver training organisation in the world), wreck diving is their single most popular speciality diving course.
Wreck diving speciality courses focus on the particular hazards presented by wrecks, and introduce divers to basic reel handling skills to enable them to engage in safer penetrations into the wreck. Most agencies impose a limit on recreational divers of a cumulative distance of 130 feet/40 meters of combined depth plus penetration.
Also bear in mind that shallower wrecks tend to get broken up by the elements much more quickly. Accordingly, the better preserved shipwrecks tend to be deeper. Many divers who engage in wreck diving undertake further training in deep diving as well.
 Technical courses
Divers who wish to engage in more extensive penetrations usually undertake specialist technical diver training. Two of the best known technical wreck diving courses are the Advanced Wreck Diver course from TDI (the largest technical diver training organisation in the world), and the Wreck Penetration Diver course from NAUI.
 Certification agencies
Recognised recreational certification agencies include:
 Get in
For a general synopsis of this topic, see the relevant subsections under Scuba diving - Get in and the national and regional dive guide articles. A general listing of national dive guide articles can be found under Scuba diving — Destinations, and some of these will list regional dive guide articles in their destination sections.
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Wreck diving is an attractive activity for scuba divers for several different reasons:
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In addition to conventional scuba diving equipment, wreck divers will normally carry additional items of kit.
Wreck divers also try to configure their kit so as to minimise "danglies", or any item of kit which might snag on the wreck, or any monofilament which may be lying around on the wreck. When penetrating a shipwreck, all equipment should be clipped in and secured close to the diver's body to stay streamlined. The clips used should be of a type which can not accidentally clip onto a line (those are known as suicide clips by cave divers), or should be weak enough to be broken free if they get snagged.
 Stay safe
In addition to general safety advice relating to diving (as to which, see Scuba diving - stay safe) wreck divers face a number of hazards in addition to those present in conventional scuba diving. Overhead environments may prevent direct access to the surface. Sharp edges may be present on the wreck. Some wartime shipwrecks may contain explosive cargos, and some wrecks may contain toxic materials or pollutants. Wrecks are also a magnet for fisherman, due to the fish that often gather on them, and fishing line and nets may become snagged on the wreck and present an entanglement risk for divers.
Most wrecks are slowly disintegrating. The structure becomes weaker as the material corrodes or rots, and at some stage it will collapse. This is not a good time to be inside. Those wrecks which are exposed to rough sea conditions will generally deteriorate faster, but oddly enough, are also usually less of a risk for collapsing on divers, as this usually happens during a storm when no divers are around. The wrecks that are below the wave action are the ones which are more likely to collapse without warning, possibly when an unlucky diver bumps againat a critically weakened structure, and precipitates a collapse. This is very unusual, but remains a possibility, and is one of the reasons why divers should be adequately trained before attempting penetrations — it helps if you can recognise some of the signs of impending structural failure.
In conditions of poor visibility it is possible to accidentally penetrate some wrecks. If you are lucky, you will also accidentally find your way out again. If you are suitably skilled, you may also find your way out. When diving at a site where this is a possibility, it is prudent to tow a surface marker buoy on a line, or tie off a line at a point known to be outside the wreck before venturing too close in the darkness. Your line is the only guarantee of a way out.
 Basic safety precautions
All diving involving overhead environments is inherently more risky. Cave divers are taught the following mnemonic in relation to ways in which the risks can be minimised: The Good Divers Are Living (or sometimes: The Good Divers Always Live).
Many popular diving wrecks have suffered over the years due to the depredations of souvenir hunting divers. In the past, many areas have had a culture of artefact removal from wrecks, but more recently there has been far greater emphasis on preserving the historical nature of the wrecks. Many countries now impose stiff criminal penalties on divers who remove artefacts. Other wrecks have suffered over the years due to heavy usage by divers and the resultant accidental impacts.
Although increasingly less common, some wrecks which attract divers still contain human remains. Divers are well advised to respect the last resting place of the people who perished when the vessel sank.
Divers should strive to abide by the following basic guidelines when on wrecks:
Some dive organisations promote a diving variant of the leave no trace motto: "take nothing but photographs, leave nothing but bubbles."
Specific guidance to local wreck legislation may be found in some of the national dive guide articles: