What is the function of a dive computer?

A dive computer serves to track depth and underwater time, which is essential for monitoring a diver's exposure to pressure and ensuring safe ascent rates. By continuously measuring the depth and time spent underwater, it helps divers avoid decompression sickness by providing real-time information about how long they can remain at specific depths and when to ascend. This ability to calculate no-decompression limits and provide alerts for ascent is crucial for safety during dives.

While other functions mentioned in the options, such as calculating buoyancy or recording marine life observations, are important aspects of diving, they are not the primary purpose of a dive computer. Similarly, evaluating water temperature is useful for divers to understand their environment but does not encompass the primary functionality of dive computers. Therefore, the tracking of depth and underwater time stands out as the central function.