What common piece of equipment assists in monitoring multiple gas mixtures during a dive?

The multi-gas dive computer is designed specifically to monitor various gas mixtures during a dive, making it an essential piece of equipment for divers using enriched air (Nitrox) or other gas mixtures. This device allows divers to keep track of the different gases they are breathing, their respective partial pressures, and the remaining bottom time based on the current gas mixture. It provides critical information on safe dive limits, ensuring divers can manage their nitrogen absorption effectively while reducing the risk of decompression sickness.

In contrast, the other options do not fulfill the same role in monitoring gas mixtures. A pressure gauge primarily measures the pressure of the air or gas supply in the tank but does not track the specifics of gas mixtures. A wrist compass aids in navigation underwater, helping divers orient themselves and navigate their route, but it does not provide any information about gas compositions. Fins are crucial for movement and propulsion in the water but have no functionality related to monitoring or managing gas mixtures.