Underwater orienteering is an underwater sport that uses recreational open circuit scuba diving equipment and consists of a set of individual and team events conducted in both sheltered and open water testing the competitors' competency in underwater navigation. The competition is principally concerned with the effectiveness of navigation technique used by competitors to swim an underwater course following a route marked on a map prepared by the competition organisers, a compass and a counter meter to measure the distance covered. The sport was developed in the Soviet Union during the late 1950s and is played mainly in Europe. It is known as Orientation Sub in French and as La Orientación Subacuática in Spanish. Historically, the sport has also been known as Technical Disciplines.
Equipment
Each competitor has the following recreational diving equipment: a diving mask, fins, a diving weighting system, an open circuit scuba set including diving cylinder filled with only breathing air of atmospheric origin and the following instruments: underwater compass and distance counting meter. Each competitor also must tow a buoy to identify his/her position underwater at all times when in the water. Competitors in the Monk Competition (refer below) are permitted to use one buoy between a pair of competitors provided a buddy line is used (i.e. wrist to wrist). An exposure suit (i.e. wetsuit with hood) is required where the water temperature is less than .
Competitors are not permitted to use underwater search techniques and aids (such as rope assisted searches or sonar) or to use underwater communication devices.
The equipment used in this sport has evolved since the sport's creation in order to improve competitor performance. Firstly, all of the scuba equipment and instruments are usually mounted together in a housing to create a streamlined form that can be held in front of the competitor to reduce resistance whilst swimming underwater and with a bracket to locate the instruments in front of the competitor allowing use whilst swimming and navigating the event courses. Secondly, competitors use monofins in order to move faster underwater.
Competitors are permitted to use survey equipment such as a theodolite or a total station to check maps issued by the competition organisers with exception to the maps for the Monk Competition (refer below). Competitors are not permitted to check distances and directions by swimming or operating a boat on the course.
Competition area
The competition is usually held in natural water bodies such as freshwater lakes. Site selection criteria include a maximum current of /minute, water depth no less than , underwater visibility to be at least (measured with a secchi disk) and water quality is to be in accordance with World Health Organization requirements for bathing water. Competition sites are not permitted to be located in shipping lanes and areas intended for boating and swimming activity. When in use for competition, the site is marked by buoys anchored from the course.
Events
Four individual events and three team events are described in the International Rules.
Individual events
The M-Course is a ‘M’ shaped course of a total length of consisting of a starting buoy, three rounding buoys and a finish line. Competitors are required to swim underwater around the rounding buoys in sequence and cross the finish line within the time limit of 15 minutes 20 seconds. Competitors are ranked using a point scoring system for correctly rounding the three buoys and for course accuracy at the finish line.
The 5-Point Course is a course of a total length of consisting of a starting buoy and five orienteering points of which the last is the finish, all laid out in an irregular shape. Competitors are required to swim underwater around the course in sequence and to confirm the discovery of each orienteering point ‘by clearly pulling or spinning it’. Competitors are ranked using a point scoring system for each orienteering point found and for the speed of the swim around the course.
The Star competition is a star-shaped course of a total length of consisting of a starting buoy, five rounding buoys and five orienteering buoys of which the last is the finish. Competitors are required to swim underwater around the course in sequence and to confirm the discovery of each orienteering point ‘by clearly pulling or spinning it’. Competitors are ranked using a point scoring system for correctly rounding the five buoys, for each orienteering point found and for the speed of the swim around the course.