Full-duplex has the potential to double the capacity of point-to-point communication links, but these benefits can only be fully realised in communication networks through development of a suitable medium access control layer. Cancellation of self-interference is a significant challenge and has been limited to antenna separation in underwater systems. Other approaches include circuit (analogue domain) and digital cancellation. Although these have yet to be fully investigated for underwater acoustic transmission, they have great potential. This PhD will explore how full-duplex communication might be exploited at the MAC layer. Simulation based modelling and performance evaluation will be undertaken, backed up by mathematical analysis, for typical scenarios with envisaged full-duplex capability. New protocols will be developed which use the full-duplex links to mitigate hidden/exposed node problems, and enhance MAC layer throughput and delay.