A dive computer with a free dive mode and/or wireless data transmission capabilities. In one embodiment the invention relates to a diving apparatus including a dive computer having a free dive mode, where the dive computer is configured to calculate a nitrogen loading in the free dive mode using a default value which is the fraction of oxygen in air, and where the free dive mode is used when a diver makes a dive without a self-contained underwater breathing apparatus. Another embodiment includes a method of operating a dive computer including recording two or more first identifiers, receiving pressure information from two or more pressure transmitters, the pressure information comprising second identifiers and pressure measurements, determining whether the pressure information contains one of the two or more first identifiers, and displaying a message indicative of the pressure information that contains one of the two or more first identifiers.