Dive computers in accordance with embodiments of the invention are disclosed. One embodiment includes a 
microprocessor, a pressure 
transducer connected to the 
microprocessor, a 
microphone connected to the 
microprocessor, a speaker connected to the microprocessor, a telephone 
transceiver connected to the microprocessor, a 
GPS receiver connected to the microprocessor and a display. In addition, the microprocessor, pressure 
transducer and display are configured to display information concerning the 
dive computer's depth of submersion, the microprocessor, 
microphone, speaker and telephone 
transceiver are configured to enable the 
dive computer to be used as a telephone 
handset, and the microprocessor is configured to obtain GPS coordinates from the 
GPS receiver. In a further embodiment, the microprocessor, the 
microphone, the speaker, the telephone 
transceiver, the display, and the 
GPS receiver are components of a 
mobile phone handset including an external connector for communicating with external devices, the pressure 
transducer is packaged separately from the 
mobile phone handset and the pressure transducer packaging includes a connector configured to mate with the external connector of the 
mobile phone handset creating a connection between the pressure transducer and the microprocessor, and the mobile phone handset and the pressure transducer are contained within a waterproof housing. In addition, a 
software application installed on the mobile phone handset configures the microprocessor to 
record information concerning the 
dive computer's depth and time of submersion in a dive log.