ROV operations are expensive and there is an urge to improve on their efficiency and speed. The EU project “Effective Dexterous ROV Operations in Presence of Communications Latencies (DexROV)” proposes a solution to those needs by developing a set of hardware and software tools to support the teleoperation of ROVs over a satellite link, i.e., from remote locations including off-shore sites. A core challenge is the significant amount of data that must be transmitted to the distant Mission Control Center to allow this. To ease operation in general and especially in this application case involving latencies in the control, a 3D model of the environment that is generated during the mission by sensors on the ROV is to be transmitted. This paper focuses on using a 3D grid map for this purpose and especially its efficient transmission under significant bandwidth constraints.