By Andy Davis

Images by Gregory S. Long

Discover what the various wreck diving levels entail, from recreational to advanced technical wreck diving.

The appeal of shipwreck diving is known to many scuba divers. Wrecks attract diverse and plentiful marine life, whilst offering a portal into maritime history. For some divers, exploration inside the remains of sunken ships is a natural continuation of that sense of discovery. Wreck penetration appeals to the explorer’s spirit.

Wreck penetration is, however, a diving activity that holds a significantly higher risk than open water scuba diving. Entry into an overhead environment, where direct ascent to the surface becomes impossible, distances the diver from any immediate recourse to quickly surface, should the equipment malfunction. It is easy to get disorientated and lost inside a shipwreck, which could cause the diver to run out of gas before an exit can be found. There is also the risk of collapsing structures, entanglement in wiring and lines or silt that removes all visibility. Consequently, formal courses exist to train divers how to safely and assuredly penetrate wrecks. These wreck diving courses have a lot in common with cave diving, as many of the risks involved are similar and near-identical protocols, skills and procedures are used to ensure diver safety.

The first level of wreck diving is to remain outside the wreck. The diver stays in an open water environment and enjoys external exploration of the sunken vessel and the marine life surrounding it. No specific training is essential at this level, but most diving agencies offer wreck appreciation or entry-level wreck training that is not specifically focused on penetration into overhead environments. There are also more academic courses, such as shipwreck survey techniques and underwater archaeology. For many recreational divers, this first level of wreck diving more than sates the appetite for exploration.

Basic wreck diving courses educate divers about the intrinsic risks of diving on shipwrecks, provide information on navigational techniques and highlight the potential legal issues involved with diving into or recovering artefacts from wrecks. Whilst some courses may introduce basic wreck penetration concepts, the training is generally minimal and best seen as educating or warning divers about the complexity and demands of wreck entry, rather than enabling them to proficiently conduct wreck penetration dives.

These entry-level wreck diving courses often qualify divers to penetrate wrecks into the daylight zone and have additional limitations based on the total distance (vertical and horizontal) to the surface, along with prohibitions on entering confined spaces. Divers should only venture into areas of a size where two divers could pass through together whilst sharing air. If the space is smaller than this, it would be categorised as a restrictive entry.

Training at this level is generally known as recreational wreck diving. The daylight zone is generally defined as areas inside a wreck where the diver can see daylight through the exit point. The diver should not venture into areas where they do not have a clear and direct line-of-sight to their exit point. In that respect, a basic wreck diver course is potentially equivalent to a cavern diving course. However, for many diving agencies, cavern diving courses are far more focused on penetration in their scope and generally include more actual penetration dives as part of their syllabus than basic wreck diving courses.

Even when restricted to the daylight zone, wreck diving students are taught basic techniques for running a guideline from outside the wreck and along their route of exploration. This guideline ensures that they can always return to the exit and helps to prevent the diver from getting disorientated or lost. The line becomes absolutely critical should an unforeseen loss of visibility occur when inside the wreck. Shipwrecks often attract silt deposits which, when disturbed by passing divers, can cloud the water. This is known as a silt out. Even if divers do not disturb silt deposits lying on the bottom, their passage through the water and the rise of their bubbles can often disturb fine sediments inside the wreck. The use of guidelines is a proven lifesaver in both the wreck and cave diving environments. Divers are also taught the need for adequate lighting and to carry a reserve torch. Many agencies advise divers to use redundant air sources; such as pony cylinders, back-mounted doubles or side- mount systems, as air-sharing inside a wreck can be substantially more difficult than in open water. The self-sufficiency to cope with equipment malfunctions and gas loss is highly advisable.

In common with cavern or cave diving, wreck penetration demands a refined core skillset of foundational scuba diving skills. In particular, the diver should possess exemplary buoyancy and trim control as well as the ability to propel themselves without kicking up silt and reducing visibility. Prospective wreck penetration divers should commit themselves to a focused practice of maintaining a stable horizontally-trimmed hover at all times and learn propulsion techniques such as the frog kick, modified flutter kick, helicopter turn and back kick for reversing.

At recreational diving levels, buoyancy control to within 1m of the desired depth might be considered the minimum level of proficiency. As the diver progresses into more advanced wreck penetrations at higher levels of training, buoyancy control should consistently be within 25cm. Trim control, namely the angle of the diver’s body in the water, needs to remain perfectly horizontal or slightly head down. This prevents water movement from fin thrusts from unsettling silt deposits. Any tendency to drop into a “feet down, head up” position when not moving must be eliminated through practice.

Situational awareness and team diving are also critical skills for wreck penetration divers. In the overhead environment,  the ability to consistently monitor gas supplies, bottom-time, navigation and the welfare of dive buddies become much more urgent. The added stress and task loading of entering a shipwreck can easily degrade such awareness if the diver has not ingrained those skills to an instinctive level of function. Wreck divers must never let themselves get fixated on a single issue to the exclusion of everything else that is happening around them.

Entering wrecks requires teamwork amongst divers. There are varied tasks to be distributed amongst the penetrating teams and the need for effective communication is paramount.

All members of the diving team need to be predictable in their protocols and procedures; not least in their responses to foreseeable emergencies. The most capable of wreck penetration teams will ensure that such drills and skills are practiced routinely in open water and/or on dry land before relying on them as potential lifesavers inside a wreck.

Wreck courses often teach core principles about the types of equipment suitable for wreck diving. The need to streamline equipment and prevent entanglements is important. Gauges and alternate air-sources should never be allowed to dangle. Divers should avoid using clips like swing-gate carabiners, which may unintentionally capture a loose line or wiring around the wreck. Even small modifications, such as securing loose fin straps with duct tape, can prevent an entanglement in a wreck. Pistol-grip torches conflict with handling reels when laying the guideline; whereas smaller torches can be worn on a hand-mount, even when using a reel. Wearing a snorkel provides more chances for snagging lines, so they might be left behind if not essential or stowed in a pocket. Smaller, stiffer fins provide better control than longer, more flexible or split fins.

Beyond entry-level wreck courses, there are training courses that develop wreck diving techniques to permit divers to penetrate beyond the daylight zone and through confined areas. These are often named advanced or technical wreck courses. The training prerequisite for these courses is generally a qualification in accelerated decompression diving, for instance the PADI Tec 45 or Advanced Nitrox/Decompression Procedures courses. This is because the extensive penetration of wrecks demands longer bottom times and technical diving equipment provides the necessary life-support redundancy.

Technical wreck training demands a robust core skillset beyond that of recreational wreck diving levels. The diver should be completely familiar and experienced with diving in technical rig equipment and planning and conducting accelerated decompression. Their team diving skills, precision-orientated mindset and sense of caution should be refined over multiple demanding training courses and substantial diving experience.

The art of laying guidelines is expanded substantially on technical wreck courses. The diver is taught how to effectively plan a route through complex areas, laying their line to promote an unimpeded and swift exit under even zero visibility. In practice sessions on the course, they will lay and retrieve lines, then progress to traverse along the line in blacked-out masks to simulate zero visibility. Further training is then provided on using tactile (touch-contact) communications and air-sharing with no visibility whilst exiting along the guideline.

Technical wreck divers also learn a set of contingency drills that provide them with the confidence to survive in worst-case scenarios. These include how to conduct searches for a lost guideline and/or a missing team member and how to deal with entanglements in the guideline. These drills involve the use of a back-up safety reel that all technical wreck divers will carry. They will be educated on the decision-making process that dictates whether decompression cylinders should be carried inside the wreck or left staged at the entry-point. Some technical wreck courses also teach techniques for using stage cylinders, which is the name given to additional cylinders of bottom gas used for a prolonged bottom time.

Precision dive planning and gas management also become critical at the technical wreck diving level. It is very important that the divers have researched the wreck layout and intended route. This allows them to accurately plan for sufficient bottom-time and the resulting decompression to complete their intended penetration and return safely, whilst retaining a one-third reserve of their gas supply. Generally, technical wreck penetrations require at least the application of the rule of thirds: allowing one-third of gas for entry, one-third for exit and one-third held  as an emergency reserve. For some wreck penetrations involving very confined areas, the divers may opt for a more conservative approach and retain a larger reserve.

Divers within a team have to match gas based on the expected volume of gas consumption to ensure that every diver retains a sufficient emergency gas reserve to get any team member out of the wreck, regardless of the differing air consumption rates and/or cylinder sizes. Technical wreck divers will always carry at least two primary cylinders with independent regulators for adequate redundancy. They will carry a primary light and two reserve lights, each of which will have a sufficient power duration; at least double that of the intended penetration time. Technical wreck courses generally include drills where the primary light fails and a reserve light must be deployed within a time limit. Cutting devices are important in the wreck environment, so divers will carry at least two, both of which need to be accessible by either hand.

Technical wreck diving courses educate divers on how to customise their diving equipment for the wreck environment, with particular attention on simplicity and to reduce or eliminate any chance of the equipment getting tangled in lines or wiring or caught in obstructions. Side-mount diving equipment is proving very popular in this respect, as it allows for cleaner progression through more confined areas inside the wreck; whilst removing tangle and damage-prone valves from behind the diver’s head.

Beyond technical wreck training, some diving agencies have further expedition-level wreck courses that prepare the diver for deeper wreck penetrations, using helium and/or closed-circuit rebreathers. There are also courses which specifically teach techniques for penetrations using multiple stage cylinders of bottom gas where the cylinders will be partially used and left clipped on the guideline as divers progress through the wreck to be recovered and used on return. Advanced side-mount courses also exist to develop specific overhead environment skills for side-mount qualified divers. These courses include training on how to pass through extremely small, restricted areas where cylinders may need to be detached and pushed ahead of or pulled behind the diver. Teams may shuttle and pass cylinders through tight restrictions to provide access to previously unexplored areas of the wreck. The level of skill and experience needed to manage these incredibly complex dives make them a truly elite level of diving.

Wreck diving, and particularly penetration inside wrecks,  is a demanding challenge for those divers who wish to pursue a desire for exploration and discovery. There are a range of specialist wreck courses available to progress the diver all the way to the most extreme levels of wreck diving, providing highly refined techniques and equipment that ensure a high degree of safety despite the increased risks involved in the dives conducted. The emphasis of wreck diving training should always be on understanding and mitigating the  risks involved. Shipwrecks are unforgiving environments for scuba divers and history has proven that the unwary or overconfident can easily become another accident statistic if something goes wrong beyond their skill, experience, training and the ability to cope under pressure. Experienced wreck divers do not accept higher risks as they seek the correct training and equipment to manage those risks and preserve their safety.