The simplest assembly of diving equipment is that used by snorkelers – a mask, snorkel and a pair of fins. In colder climates, a wetsuit may be added for thermal insulation and a weight belt to compensate for the buoyancy of the suit. In tropical waters, a ‘stinger suit’ provides not only a little thermal comfort but also some protection from box jellyfish and other stings.
A mask is needed to give the diver adequate vision underwater. The mask usually covers the eyes and nose. Traditionally, masks were made from rubber, although now most are made from silicone. The mask seals by pressing on the cheeks, forehead and under the nose with a soft silicone edge to prevent entry of water. Swimming goggles, which do not cover the nose, are not suitable for diving. The nose must be enclosed in the mask so that the diver can exhale into it to allow equalization of the pressure between the face and mask with the water environment. It should be possible to block the nostrils without disturbing the mask seal to enable the wearer to perform a Valsalva manoeuvre. Full-face masks that cover the mouth as well as the eyes and nose, or helmets that cover the entire head, are more commonly used by professional divers and are considered in the section on professional diving equipment.
The faceplate of the mask should be made from hardened glass. A diver with visual problems can choose from a selection of corrective lenses that are commercially available. These are designed to attach directly to certain masks.
Alternatively, prescription lenses can be ground and glued to a variety of masks. Ocular damage can occur if hard corneal lenses are used for diving (see Chapter 42). Certain contact lenses may be lost if the mask floods and the diver fails to, or is unable to, take preventive action. Some people with allergy problems react to the rubber of the mask, although this is rarely an issue with silicone.
All masks cause a restriction in vision. With most masks, the diver can see about one third of his or her normal visual field. The restriction is most marked when the diver tries to look down toward the feet. This restriction can be a danger if the diver becomes entangled. However, there are some masks available with a tilted lens to provide a better downward field of vision.
The more nervous beginner may find the visual restriction worrying and may possibly fear that there is a lurking predator just outside the field of vision. The visual field varies with the style of mask. Experimentation is also needed to find which mask gives a good seal, to minimize water entry. The diver needs to master a technique to expel water from the mask. If it is not learned and mastered, a leaking mask can become a major problem, sometimes leading to panic.
The typical snorkel is a tube, about 40 cm long and 2 cm in diameter, with a pre-moulded or creatable U-bend near the mouth end. A mouthpiece is fitted to allow the diver to grip the tube with the teeth and lips. The tube is positioned to pass upward near the wearer’s ear to enable him or her to breathe through the tube while floating on the surface and looking down. Any water in the snorkel should be expelled by forceful exhalation before the diver inhales through the snorkel.
Many attempts have been made to ‘improve’ the snorkel by lengthening it, adding valves, modifying its shape and some other means. There is little evidence of the success of most of these attempts.
All snorkels impose a restriction to breathing. A typical snorkel restricts the maximum breathing capacity to about 70 per cent of normal. The volume of the snorkel also increases the diver’s anatomical dead space. Because of this, increasing the diameter substantially to reduce the resistance is not a viable option. These problems add to the difficulties of a diver who may be struggling to cope with waves breaking over him or her (and into the snorkel) and a current that may force the diver to swim hard. There have also been anecdotal reports of divers inhaling foreign bodies that have previously lodged in the snorkel.
Fins (or flippers) are mechanical extensions of the feet. Fins allow the diver to swim faster and more efficiently, and they free the diver’s arms for other tasks. The fins are normally secured to the feet by straps or are moulded to fit the feet. Various attempts have been made to develop fins that give greater thrust with special shapes, valves, controlled flex, springs and materials, all competing for the diver’s dollar. Some of these fins can improve the thrust, but the wearer needs to become accustomed to them. Others have little effect.
Divers often get cramps, either in the foot or calf, if fins are the wrong size, if the diver has poor technique or if the diver has not used fins for an extended period. The loss of a fin may also cause problems for a diver, especially if he or she has to a swim against a current, or fails to attain appropriate orientation underwater or buoyancy on the surface.
Even without the buoyancy of a wetsuit, some divers require extra weights to submerge easily. The weights are made from lead, and most are moulded to thread onto a belt. Some weights are designed to fit into pouches, either on a belt or, for scuba divers, attached to a buoyancy compensator device (BCD). Whatever weighting mechanism is used needs to be fitted with a quick-release buckle or other mechanism to allow a diver to drop the weights quickly and so aid his or her return to, or enable the diver to remain on, the surface. The situations in which a quick-release buckle may not be fitted (or may be de-activated) are those where it would be dangerous to ascend, such as in caves where there is no air space above the water.
In some circumstances, it is necessary for a diver to ditch the weight belt to reach, or remain on, the surface in an emergency. Such situations include an emergency in which the scuba diver cannot inflate the BCD, for example, if the diver is out of breathing gas. Unfortunately, divers often fail to release the belt if they are in difficulty. The reason for this omission is not clear, but it is likely often the result of stress or panic. Adequate initial training and practice help to reinforce the skill so that it will become more automatic when required. It also needs to be reinforced periodically. Unfortunately, much of the current training fails to focus adequately on this important emergency drill.
An alternative drill of taking the belt off and holding it in one hand (preferably away from the body) is useful in some situations in which the diver is likely to become unconscious and inflating the BCD is not an option or may not be sufficient (e.g. when deep). In the event of unconsciousness, the belt will hopefully fall away, causing the diver to rise to the surface. Holding the belt away from the body should reduce the chance of entanglement with the diver if it is dropped.
In many fatal diving accidents the diver did not release his or her weights.
This basic free diving equipment is adequate for diving in shallow, relatively warm water. Experience with this gear is excellent training for a potential scuba diver. The diver can gain the basic skills without the extra complications caused by scuba gear. It allows a more realistic self-assessment of the desire to scuba dive and the subsequent rewards. With the confidence gained in snorkeling and breath-hold diving and the associated aquatic skills, the diver is also less likely to become as dependent on the breathing apparatus. In cold climates, a snorkel diver needs a suit to keep warm. Suits are discussed in Chapter 27.