Various embodiments associated with signal conversion while underwater are described. A source can transmit an alternating current signal with a relatively high frequency over a relatively long distance. The alternating current signal with the relatively high frequency can be converted to an alternating current signal with a relatively low frequency. An example of this conversion can be done by converting the alternating current signal with the relatively high frequency into a direct current signal. The direct current signal can then be converted into the alternating current signal with the relatively low frequency. The alternating current signal with the relatively low frequency can be transmitted from a transmission coil to a pick-up coil. After reception by the pick-up coil the alternating current signal with the relatively low frequency can be processed, such as processed to determine a direction of the source of the alternating current signal with the relatively high frequency.