Disclosed are embodiments of methods and systems for wireless data transmission by magnetic induction. In one embodiment, a network of magnetic induction units is provided. The units may be configured to transmit a data signal by modulation of a time-varying magnetic field. One or more units may also be configured to receive a data signal received from another magnetic induction unit. In one specific implementation, a network of underground magnetic induction units is provided, each having a sensor connected thereto. Each of the units, or a subset of the units, may be configured to transmit its sensed data to an adjacent or nearby unit, which, in turn, may retransmit the original data, along with additional appended data, to another adjacent unit. The network data may thereby be relayed in a multi-hop fashion until it reaches a desired destination.