Scuba divers use an underwater compass and natural navigation (e.g. observation techniques) to help them reach a destination point when diving.
This guide contains a list of underwater navigation equipment used by divers, with simple tips for beginners about how to use a compass to navigate underwater.
Divers learn how to navigate underwater in entry-level scuba courses, albeit to a limited degree.
This kind of orienteering is a matter of training and familiarity with the use of underwater compasses, combined with:
Pro Tip: Freedivers see the importance of compass in diving as mostly unnecessary, due to the short time periods spent underwater. Plus, the limited distance that surface supplied divers can travel also places less significance for using an underwater diver navigation device.
Underwater navigation is the common reference term for navigating skills and techniques learned by scuba divers so they can accurately traverse underwater environments.
It is a core component of advanced training for recreational divers. For example, the PADI® Advanced Open Water Diver requirements include a mandatory navigation dive skill that involves underwater compass navigation.
The PADI Underwater Navigation Specialty course contains three (3) scuba training dives that focus on underwater search patterns, such as the expanding square and the semi-circular sweep.
There are several reasons why scuba divers learn how to use a diving compass during their training. Not only does successful orienteering underwater help to build confidence in a diver, it also:
Beginners will find it easier to separate the skills into three types, being natural, instrument, and a combination of the two - called practical navigation.
Scuba divers use a similar referencing process to the one that mariners use in pilotage, or piloting. In other words, divers orient themselves using observable landmarks and natural features, such as:
Instrument navigation (e.g. using a scuba diving compass underwater) is the most popular technique that novices use for distance estimation and orienteering.
Even though a compass navigation tool is commonplace, and relatively accurate, other devices and mechanisms include:
In most cases, some kind of combination of the two methods (a hybrid version) will be best for most recreational divers.
Hence, we use diving compasses to navigate longer distances and in poor visibility, and natural navigation between topographical structures, marine life habitats, and other man-made landmarks.
Here's the thing:
Often, returning to a specific place is important for safety. In this case, divers lay a distance line in place and leave it there for other divers to use, before recovering it on the final return leg.
Pro Tip: Using distance lines is standard safety practice for deep wreck penetration dives and for cave and cavern diving. In fact, being able to make an ascent directly to the surface would be impossible in these hazardous diving environments.
A magnetic compass is a reliable navigational tool because it works by indicating the local direction of the ambient magnetic field (the Earth). Thus, pressure changes, decreased visibility, and the presence of water do not affect its use.
Following these simple steps will help you use an underwater diving compass in a reliable and effective manner:
Pro Tip: It can be difficult to read the graduations on an analogue compass in low visibility. However, the display on a digital compass can be clearer and it uses a magnetometer to detect the magnetic field of the Earth.
Magnetic compasses are one the most common and cheapest scuba diving accessories that divers use to navigate their way around. You can buy them as a wrist mounted device or pre-set in a diver's console. Other tools that can be used to plot an ongoing course during a dive include:
A course plotter, or nav-finder, is used in scuba diving to track a multi-heading course and then return to the start point. You can also use the complex patterns to find your way from one of the points to another, or for:
The direction is determined using a magnetic compass. The distance can be measured by noting either the 'time' or 'kick cycles'. Thus, divers need to swim at a constant speed to get maximum accuracy.
Pro Tip: The latest developments in underwater GPS tracking for scuba divers are improving each year. In fact, modern technology knows the exact latitude and longitude of a diver and it can display a map of the underwater terrain (where available).
Pro Tip: The short video tutorial [8:51 seconds] presented by Divers-Supply explains more about basic scuba diving compass use and underwater navigation techniques for new and experienced divers.