A dive computer is an electronic device that runs an algorithm every 15-30 seconds that calculates your nitrogen/oxygen/helium absorption at a given depth and time. It measures things like depth, dive time, and ascent rate. The algorithm in computers enables you to stay safe underwater and minimises decompression sickness. Scuba diving computers come in both wrist and console models. Console models are larger and attach to your first stage, they always include a submersible pressure gauge (SPG), while wrist models are smaller and are worn on your wrist.