UNDERWATER COMMUNICATION DEVICE AND UNDERWATER COMMUNICATION SYSTEM

A underwater communication device communicates data with another underwater communication device having another first coil and another second coil in water. The underwater communication device includes a first coil configured to transmit the data to and from the other first coil via a magnetic field, a second coil configured to transmit the data to and from the other second coil via a magnetic field, a supply unit configured to supply the data to the first coil and the second coil, a first capacitor connected to the first coil and forming a first resonance circuit that resonates with the first coil at a first resonance frequency, and a second capacitor connected to the second coil and forming a second resonance circuit that resonates with the second coil at a second resonance frequency that is different from the first resonance frequency.