Many divers take diving compasses for granted, considering them just an accessory to an overall dive gauge console system. Trying to navigate with a poorly designed or improperly functioning compass can be one of diving's more frustrating events. We use and recommend the Suunto range of wrist and bungee mount dive compasses.
Compass Balance Zones
Compasses are designed for use within a certain area of the globe because the earth's magnetic field not only varies horizontally, but also vertically, causing the needle to dip downward when the case is held level. The compass needle card is balanced with a small weight to counteract the downward dip so the needle card does not drag or stick on the top or bottom of the capsule. If you take any compass to a significantly different part of the globe than where it was balanced, check the compass carefully before relying upon it. The compasses we sell are balanced for the southern hemisphere.
Note that digital compasses, like the ones becoming popular in dive computers, do not have balance zones. Digital compasses are universal because they have a user 'calibration' feature, which is performed in the region where the diver plans to use the compass. A change in region simply requires a recalibration before use in the new location