Describe the function of a dive computer.

A dive computer plays a crucial role in scuba diving by monitoring depth, time, and decompression status throughout a dive. It continuously calculates and displays essential parameters related to the diver's current depth and the time spent at that depth, which helps prevent decompression sickness by ensuring that the diver does not ascend too quickly and allows for safe ascent profiles.

By keeping track of the cumulative nitrogen absorbed by the body, dive computers provide real-time information regarding decompression limits, which is vital for planning safe ascents and making necessary safety stops. This advanced tracking capability significantly enhances diver safety and allows for more extended and varied diving experiences while adhering to safe diving practices.

In contrast to the other functions presented, underwater navigation, measuring water temperature and salinity, and providing emergency communication are either secondary functions of dive computers or unrelated to their primary purpose. While some dive computers may have additional features like navigation aids, temperature sensors, or connectivity for emergency communication, monitoring depth, time, and decompression status remains the fundamental and critical function that serves to ensure the safety of the diver.