In one aspect, a mobile device comprises a transceiver and a controller. The transceiver communicates with another device in a plurality of frequency bands. The plurality of frequency bands includes a first frequency band and a second frequency band. The first frequency band has a lower frequency than the second frequency band. The controller uses the first frequency band in preference to the second frequency band in a first case where an own mobile device is estimated to be immersed in water based on a value detected by at least one sensor. The controller uses the second frequency band in preference to the first frequency band in a second case where the own mobile device is not estimated to be immersed in water based on a value detected by the at least one sensor.