Check shots were done at the base of logged holes using the Inline Checkshot Tool as part of wireline logging operations. Table T2 shows the average velocity between the base of the hole and the seafloor (using the traveltime to the seafloor measured from the 3-D reflection data, which is shown in Figs. F4, F8, and F10). These velocities are generally consistent with the velocities obtained from the VSPs and show a general increase in velocity with depth. These velocities can be used for depth conversion at Site 1245, at which a full VSP was not successful because of hole instability, and further supports the conclusion that there is no thick widespread free gas zone beneath the BSR at South Hydrate Ridge.