Figure 1. To image a target at depth D, the distance X from the source to the farthest receiver should equal or exceed D. Two options are shown for acquiring long-offset marine seismic data: super-long towed-cable technology and stationary ocean-bottom sensors (OBS) deployed on the seafloor. Seafloor sensors can be deployed as individual sensor packages with self-contained data storage or as long ocean-bottom-cable (OBC) linked to a recording boat.