A system to manage an optical link in free-space to communicate data via an aqueous medium, comprising: a seismic data acquisition unit positioned on a seabed in the aqueous medium, the seismic data acquisition unit comprising: one or more sensors to detect acoustic waves that indicate subsurface lithologic formations or hydrocarbon deposits; a seismic data recorder to record seismic data corresponding to the acoustic waves detected by the one or more sensors; and a second link manager agent, a second optical receiver and a second optical transmitter; and of an underwater vehicle comprising a first link manager agent, a first optical transmitter and a first optical receiver characterised in that the underwater vehicle is configured to receive, through the aqueous medium from the seismic data acquisition unit, an optical transmission at a default time interval; transmit, to the seismic accusation unit, a first optical transmission at a first output level, the first optical transmission comprising a first packet corresponding to a network protocol; determine, responsive to receipt of the optical transmission, that the second link manager agent of the seismic data acquisition unit failed to receive the first packet via the first optical transmission; determine, based on one or more optical signals transmitted between the seismic data acquisition unit and the underwater vehicle , a distance between the seismic data acquisition unit and the underwater vehicle based on a phase error in the one or more optical signals; and transmit, responsive to failure of the first optical transmission, a second optical transmission at a second output level different than the first output level over the distance between the seismic data acquisition unit and the underwater vehicle and establish the second output level as a transmission output level for the underwater vehicle . one or more sensors to detect acoustic waves that indicate subsurface lithologic formations or hydrocarbon deposits; a seismic data recorder to record seismic data corresponding to the acoustic waves detected by the one or more sensors; and a second link manager agent, a second optical receiver and a second optical transmitter; and of an underwater vehicle comprising a first link manager agent, a first optical transmitter and a first optical receiver characterised in that the underwater vehicle is configured to receive, through the aqueous medium from the seismic data acquisition unit, an optical transmission at a default time interval; transmit, to the seismic accusation unit, a first optical transmission at a first output level, the first optical transmission comprising a first packet corresponding to a network protocol; determine, responsive to receipt of the optical transmission, that the second link manager agent of the seismic data acquisition unit failed to receive the first packet via the first optical transmission; determine, based on one or more optical signals transmitted between the seismic data acquisition unit and the underwater vehicle , a distance between the seismic data acquisition unit and the underwater vehicle based on a phase error in the one or more optical signals; and transmit, responsive to failure of the first optical transmission, a second optical transmission at a second output level different than the first output level over the distance between the seismic data acquisition unit and the underwater vehicle and establish the second output level as a transmission output level for the underwater vehicle . <EOS>