The animation shown here demonstrates the added benefit provided to the mariner when high-resolution ocean depths (bathymetry) are combined with real-time water level measurements.  The bathymetry is color coded to show those areas that are safe for the navigation of a vessel with a draft (or depth in the water) of 10 meters and a two-meter safety factor.  The green areas shown in this animation are those areas that are deeper than 12 meters (the draft plus the safety factor).  The yellow areas (which fringe the green areas) are areas where the depth is within the safety factor.  Areas in red have water depths equal to, or less than, the draft of the ship and thus are areas where grounding is likely.  One can see that as the tide goes in and out, the area available for a vessel to navigate expands and contracts.  Being able to see what water is actually available to navigate (versus a static view of the bathymetry) based on the observed or predicted tides will provide more information to the mariner, so she can schedule and execute her transit.