Wall diving

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Wall diving is underwater diving alongside a near vertical face, usually an underwater cliff. It is a type of reef diving popular among recreational divers for the biodiversity of the benthic community on the one side with a pelagic community on the other, and useful in scientific diving when assessing biodiversity of a region. No special training is required, but good buoyancy control skills are necessary for safety. Wall dive sites vary considerably in depth, and many are suitable for drift diving when a moderate current flows along the wall.

Contents

Environment

The main characteristic of wall diving sites is that the terrain is predominantly near vertical. The height of the wall can vary from a few metres to hundreds of metres. [1] The top of the wall must be within diving depth, or above the water, but the bottom may be far below or reasonably close to the surface. Many wall dive sites are in close proximity to more gently sloping reefs and unconsolidated sediment bottoms.

Topography

The wall face may be anything from a relatively smooth face, at a steep slope, through vertical to a moderate overhang, and may be a single cliff face, or stepped, or have overhangs, caves, ledges, gullies, and cracks. Rugosity may be high or low. In plan it can be anything from nearly straight to highly convoluted, with gullies, curves, sudden changes of direction, transverse canyons, and offshore stacks. A wall may be a few tens of metres long or may extend for several kilometres. [1] The structure of the wall face can be virtually any kind of sufficiently durable rock, or coral reef, and artificial structures such as dam walls, breakwaters, harbour walls, and offshore platforms may also be considered walls for recreational diving. [1]

Ecology

The basic ecology depends on the geographical location, and is usually very similar to that of the local reefs. It is also affected by the water flow and detailed topography, and by the depth range. Biodiversity tends to be higher where there are a wider range of habitats concentrated in a region, and this is generally true for walls, though they may lack organisms that prefer a more horizontal substrate, and those easily dislodged which may fall to relatively inhospitable depths. [2]

Local biodiversity may be higher than average for the region due to wide depth range and variety of habitats. Both pelagic and benthic organisms may be present. Much of the marine benthic life will usually be relatively delicate and sensitive to impact by divers and their equipment, making it undesirable to use the wall face as place to hold onto for position and depth control, though some divers routinely use reef hooks for this purpose. [3] [2]

Hazards

The most characteristic hazard of wall diving is that a lack of a depth-limiting bottom within the operational depth range may allow a diver to exceed planned depth, but this is not always a problem. [1]

Currents may follow the face of the wall both horizontally or vertically, in upwellings and downwellings, and there can be strong vortices and turbulence at sharp changes in direction, and overfalls at the top. [1] Such currents may be stable, or variable and relatively unpredictable. Large swells can make the top edge untenable if they cross the top edge, as this can generate strong turbulence and rapidly changing local up- and down-wellings. Up- and downwellings are often isolated and may be restricted to known locations and specific sea conditions, so it may be possible to avoid them much of the time. Lateral currents may be stronger further away from the wall, or near the wall around projections and sharp convex changes in direction across the current flow. Local variations in wall topography may provide shelter from currents or areas of increased turbulence which can sometimes be visually recognised by movements of benthic organisms, like sea fans or seaweeds, with the flow, or occasionally by the predominance of organisms that are suited to strong flow or turbulence [4]

A further hazard for divers towing a surface marker buoy is getting the buoy snagged on a shallow obstacle while the diver is in a strong current, as the combination of flow and restraint at the end of the line can cause a diver to swing upward rapidly, which can violate recommended ascent rate and present a risk of decompression illness.

Skills

The most universal specific skill requirement is good buoyancy control, which is needed to avoid excessive depth and rapid depth changes in either direction, particularly in the presence of turbulence and vertical flow. Good buoyancy control is facilitates by optimum weighting for tde equipment used. In general, wall diving does not require any specialist skills beyond those normally needed for the dive profile planned and the equipment used. No special training or certification is needed. [4] [3] [1]

Procedures

Recreational diving profiles planned on walls tend to start deep and gradually ascend along the wall, preferably surfacing where the depth of the top of the wall is shallow if the water movement allows, as this will usually maximise the no-stop limit, or minimise the decompression obligation for a given bottom time and breathing gas mixture.

It may be difficult to set up a shot-line conveniently near the wall face, depending on depth and water movement, and it may not be possible to moor a dive boat close enough to the wall to be useful as an ascent location. A wall is often a suitable venue for drift diving, depending on current strength and direction. The presence of the wall face is useful as a vertical reference, which may help in monitoring depth if there is not much current. Vertical areas and overhangs may make towed surface markers difficult or impossible to manage, depending on current strength and direction, wind, and wave motion, and a dive leader towing a surface marker buoy may have to stay far enough from the wall to avoid getting the line snagged on a shallower part of the wall. Decompression buoys deployed at a suitable point during ascent can be useful, even when no stops are required, for effective control of ascent rate and as a signal to boat traffic indicating the position of the divers, and that they are ascending. [1] Negative buoyancy descent down a wall face requires divers to be able to stop descending at their planned depth, which usually requires achieving neutral buoyancy by buoyancy compensator and dry suit inflation in time to stop. [3]

Environmental impact

As in the case of flatter reefs, much of the damage done by divers is by fin strikes , but the finning techniques likely to minimise impact may differ. The frog kick which helps avoid contact and disturbance below the diver is less relevant where there is no reef to impact below the diver, and a vertical or steeply inclined trim does not put the fins close to the bottom. Frog kick can increase the risk of fin strike when swimming parallel to the wall at close range, while flutter kick should normally propel the diver parallel to the reef with a relatively low risk of fin strike. [5]

The other common form of diver contact with the wall surface is holding on to control motion due to sudden or unexpected changes in water flow. Damage depends on what the diver holds onto, and how it is done. Benthic organisms vary considerably in sensitivity to this kind of contact, but unlike fin strike, the diver may have a choice of what to hold, though in strong turbulence this may no be the case.

Equipment

Most wall diving is for recreational and scientific purposes, using scuba equipment. Choice of diving equipment depends on the topography, water conditions, and hazards of the specific site, and the planned dive profile, particularly maximum depth and planned staged decompression. The main difference between wall and other forms of reef diving is that there may not be a bottom limiting the dive depth, Otherwise, the equipment is generally the same as for other open water diving in similar conditions. Decompression buoys are a relatively common choice in the open sea, for signalling position and for depth control during ascent. The dive computer or depth gauge should be carried where it can easily and frequently be checked. An audible depth alarm can be useful. [1] Good weighting and weight distribution allowing the diver to trim as suits the situation and which minimises the volume of gas necessary in the buoyancy compensator will facilitate maintaining neutral buoyancy, which may require more attention on wall dives. [6] [5]

Location

Walls suitable for diving are usually relatively close to the shore, and in some cases are a continuation of a shoreline cliff face. Most wall dive sites are in the sea, but they can also be found inland in sinkholes, caves, flooded quarries, and flooded mines. [1] [3]

Wall diving regions

Specific regions known for wall dive sites include the Cayman Islands, Palau, Indonesia, Papua New Guinea, [1] Turks & Caicos, Bahamas, Honduras, Belize, Hawaii, Red Sea, Fiji, [3] and others, including many outside the tropics. Inshore dive sites in North America with vertical rock faces include Puget Sound in Washington, Monterey Bay, and Catalina Island in California. [4]

Related Research Articles

Open water diving is underwater diving in an open water environment, where the diver has unrestricted access by way of a direct vertical ascent to the breathable air of the atmosphere. Other environmental hazards may exist which do not affect the classification. Open water diving implies that if a problem arises, the diver can directly ascend vertically to the atmosphere to breathe air, so it is also understood that, with this restriction, a staged decompression obligation is incompatible with open water diving, though it does not affect classification of the environment. This meaning is implied in the certifications titled Open Water Diver and variations thereof.

<span class="mw-page-title-main">Drift diving</span> Scuba diving where the diver is intentionally transported by the water flow

Drift diving is a type of scuba diving where the diver is transported by the water movement caused by the tide, an ocean current or in a river. The choice whether to drift dive depends on the purpose of the dive, and whether there is an option. At some sites there is almost always a current running, and at others the strength and direction of water movement may vary with the tide, or other driving forces, like wind or recent rainfall. At some sites there may be considerable variation in visibility and underwater life activity based on the speed and direction of flow.

<span class="mw-page-title-main">Surface marker buoy</span> Buoy towed by a scuba diver to indicate the divers position

A surface marker buoy, SMB, dive float or simply a blob is a buoy used by scuba divers, at the end of a line from the diver, intended to indicate the diver's position to people at the surface while the diver is underwater. Two kinds are used; one (SMB) is towed for the whole dive, and indicates the position of the dive group throughout the dive, and the other, a delayed surface marker buoy, DSMB or decompression buoy, is deployed towards the end of the dive as a signal to the surface that the divers have started to ascend, and where they are going to surface. Both types can also function as a depth reference for controlling speed of ascent and accurately maintaining depth at decompression stops. Surface marker buoys are also used by freedivers in open water, to indicate the approximate position of the diver when submerged. They may also be used to support a catch bag or fish stringer by underwater hunters and collectors. A DSMB is considered by recreational scuba divers and service providers to be a highly important item of safety equipment, yet its use is not part of the entry level recreational diver training for all training agencies, and there are significant hazards associated with incompetent use.

<span class="mw-page-title-main">Diving weighting system</span> Ballast carried to counteract buoyancy

A diving weighting system is ballast weight added to a diver or diving equipment to counteract excess buoyancy. They may be used by divers or on equipment such as diving bells, submersibles or camera housings.

<span class="mw-page-title-main">Diving shot</span> Substantial weighted near-vertical line with buoy

A diving shot line, shot line, or diving shot, a type of downline or descending line, is an item of diving equipment consisting of a ballast weight, a line and a buoy. The weight is dropped on the dive site. The line connects the weight and the buoy and is used by divers to as a visual and tactile reference to move between the surface and the dive site more safely and more easily, and as a controlled position for in-water staged decompression stops. It may also be used to physically control rate of descent and ascent, particularly by surface-supplied divers.

<span class="mw-page-title-main">Scuba diving</span> Swimming underwater, breathing gas carried by the diver

Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The name scuba is an acronym for "Self-Contained Underwater Breathing Apparatus" and was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their own source of breathing gas, usually compressed air, affording them greater independence and movement than surface-supplied divers, and more time underwater than free divers. Although the use of compressed air is common, a gas blend with a higher oxygen content, known as enriched air or nitrox, has become popular due to the reduced nitrogen intake during long or repetitive dives. Also, breathing gas diluted with helium may be used to reduce the effects of nitrogen narcosis during deeper dives.

<span class="mw-page-title-main">Diver rescue</span> Rescue of a distressed or incapacitated diver

Diver rescue, usually following an accident, is the process of avoiding or limiting further exposure to diving hazards and bringing a diver to a place of safety. A safe place generally means a place where the diver cannot drown, such as a boat or dry land, where first aid can be administered and from which professional medical treatment can be sought. In the context of surface supplied diving, the place of safety for a diver with a decompression obligation is often the diving bell.

<span class="mw-page-title-main">Diving equipment</span> Equipment used to facilitate underwater diving

Diving equipment, or underwater diving equipment, is equipment used by underwater divers to make diving activities possible, easier, safer and/or more comfortable. This may be equipment primarily intended for this purpose, or equipment intended for other purposes which is found to be suitable for diving use.

<span class="mw-page-title-main">Ascending and descending (diving)</span> Procedures for safe ascent and descent in underwater diving

In underwater diving, ascending and descending is done using strict protocols to avoid problems caused by the changes in ambient pressure and the hazards of obstacles near the surface such as collision with vessels. Diver certification and accreditation organisations place importance on these protocols early in their diver training programmes. Ascent and descent are historically the times when divers are injured most often when failing to follow appropriate procedure.

<span class="mw-page-title-main">Emergency ascent</span> An ascent to the surface by a diver in an emergency

An emergency ascent is an ascent to the surface by a diver in an emergency. More specifically, it refers to any of several procedures for reaching the surface in the event of an out-of-gas emergency, generally while scuba diving.

<span class="mw-page-title-main">Recreational dive sites</span> Places that divers go to enjoy the underwater environment

Recreational dive sites are specific places that recreational scuba divers go to enjoy the underwater environment or for training purposes. They include technical diving sites beyond the range generally accepted for recreational diving. In this context all diving done for recreational purposes is included. Professional diving tends to be done where the job is, and with the exception of diver training and leading groups of recreational divers, does not generally occur at specific sites chosen for their easy access, pleasant conditions or interesting features.

<span class="mw-page-title-main">Diver trim</span> Balance and orientation skills of an underwater diver

The trim of a diver is the orientation of the body in the water, determined by posture and the distribution of weight and volume along the body and equipment, as well as by any other forces acting on the diver. Both static trim and its stability affect the convenience and safety of the diver while under water and at the surface. Midwater trim is usually considered at approximately neutral buoyancy for a swimming scuba diver, and neutral buoyancy is necessary for efficient maneuvering at constant depth, but surface trim may be at significant positive buoyancy to keep the head above water.

<span class="mw-page-title-main">Scuba skills</span> The skills required to dive safely using a self-contained underwater breathing apparatus.

Scuba skills are skills required to dive safely using self-contained underwater breathing apparatus, known as a scuba set. Most of these skills are relevant to both open-circuit scuba and rebreather scuba, and many also apply to surface-supplied diving. Some scuba skills, which are critical to divers' safety, may require more practice than standard recreational training provides to achieve reliable competence.

<span class="mw-page-title-main">Decompression equipment</span> Equipment used by divers to facilitate decompression

There are several categories of decompression equipment used to help divers decompress, which is the process required to allow divers to return to the surface safely after spending time underwater at higher ambient pressures.

<span class="mw-page-title-main">Outline of underwater diving</span> List of articles related to underwater diving grouped by topical relevance

The following outline is provided as an overview of and topical guide to underwater diving:

Diving procedures are standardised methods of doing things that are commonly useful while diving that are known to work effectively and acceptably safely. Due to the inherent risks of the environment and the necessity to operate the equipment correctly, both under normal conditions and during incidents where failure to respond appropriately and quickly can have fatal consequences, a set of standard procedures are used in preparation of the equipment, preparation to dive, during the dive if all goes according to plan, after the dive, and in the event of a reasonably foreseeable contingency. Standard procedures are not necessarily the only courses of action that produce a satisfactory outcome, but they are generally those procedures that experiment and experience show to work well and reliably in response to given circumstances. All formal diver training is based on the learning of standard skills and procedures, and in many cases the over-learning of the skills until the procedures can be performed without hesitation even when distracting circumstances exist. Where reasonably practicable, checklists may be used to ensure that preparatory and maintenance procedures are carried out in the correct sequence and that no steps are inadvertently omitted.

Low impact diving is recreational scuba diving that is intended to minimise environmental impact by using techniques and procedures that reduce the adverse effects on the environment to the minimum that is reasonably practicable for the situation. To a large extent this is achieved by avoiding contact with sensitive reef life, but it also applies to diving on historical wrecks and in caves with delicate rock formations. It is in the interests of diving tourism service providers to help protect the condition of the dive sites on which their businesses rely. They can contribute by encouraging and teaching low impact diving and following best-practice procedures for diving in sensitive areas. Low impact diving training has been shown to be effective in reducing diver contact with the bottom, the most common cause of reef damage.

References

  1. 1 2 3 4 5 6 7 8 9 10 Laymon, Lynn. "Off the Wall: The Thrill of Wall Diving". Dive Training Magazine. Retrieved 26 July 2024.
  2. 1 2 Bravo, G.; Livore, J.P.; Bigatti, G. (23 December 2020). "The Importance of Surface Orientation in Biodiversity Monitoring Protocols: The Case of Patagonian Rocky Reefs". Front. Mar. Sci. 7: 578595. doi: 10.3389/fmars.2020.578595 .
  3. 1 2 3 4 5 "Wall Diving Essentials". www.liveaboard.com. Retrieved 27 July 2024.
  4. 1 2 3 "Wall Diving: How To Explore, Skills and Tips". La Galigo liveaboard. 23 December 2023. Retrieved 28 July 2024.
  5. 1 2 Hammerton, Zan (2014). SCUBA-diver impacts and management strategies for subtropical marine protected areas (Thesis). Southern Cross University.
  6. ↑ Jablonski, Jarrod (2006). "5: An Overview of the DIR Equipment Configuration". Doing It Right: The Fundamentals of Better Diving. High Springs, Florida: Global Underwater Explorers. pp. 66–70. ISBN   0-9713267-0-3.
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