Underwater navigation

Underwater navigation is the common reference term for navigation techniques learned by Scuba divers in order to accurately navigate in an underwater environment.

Although it is considered a basic skill, it is normally only taught to a limited degree as part of basic Open Water certification. Most North American diver training agencies only teach significant elements of underwater navigation as part of the Advanced Open Water Diver certification program.

Underwater navigation is usually a core component if most, if not all, advanced diver training. In the PADI Advanced Open Water Diver course, it is one of the two mandatory skills (together with Deep diving) which must be taken alongside three elective skills. [http://www.padi.com/padi/en/kd/advancedopenwater.aspx]

Training agencies promote underwater navigation as a skill (despite the fact that it is less popular than other recreational diving specialties) on the basis that it:
* builds diver confidence
* saves energy by minimising excess swimming
* makes dive planning more effective
* keeps dive buddies together
* reduces air consumption

Navigation techniques

Underwater navigation in recreational diving is broadly split into two categories. "Natural navigation" techniques, and "orienteering", which is navigation focused upon the use of an underwater magnetic compass.

Natural navigation involves orienting by naturally observable phenomena, such as sunlight, water movement, bottom composition (for example, sand ripples always run parallel to the shore), bottom contour and noise. Although natural navigation is taught on courses, acquiring the skills is in the ordinary course more a matter of experience.

Orienteering is a matter of training and familiarity with the use of underwater compasses, combined with various techniques for reckoning distance underwater, including kick cycles (one complete upward and downward sweep of a kick), time, air consumption and occasionally (for shorter distances), by actual measurement.

Equipment

Various pieces of equipment have developed to assist divers navigating underwater.
* Magnetic compasses, set either in a diver's console or wrist mounted. Various forms exist.
* Scuba sextant, or Nav-finder, to enable a diver to plot an ongoing course during a dive.
* Compass boards
* Hand-held sonarPeriodically reports are issued suggesting the development of underwater GPS technology, but no system is currently available on market. It is generally thought that the difficulty of locating satellite by signals from underwater at present is not capable of being overcome by existing technology.

ources

* PADI Underwater Navigation Manual (2003), ISBN 1-878663-15-1