Chlorophyll Maps - Concentrated areas of produced chlorophyll, related to phytoplankton locations.
Salinity Maps - Salt concentration in marine water, related to phytoplankton locations.
Altimetry Maps - The rising & lowering fluctuation of the sea surface, related to currents and eddy locations.
Mixed Layer Depth Maps - The depth where the density is approximately the same as the surface, and phytoplankton production occurs within the depth of shallower layers.
Bathometry/Depth Maps - The measurement of the ocean depth. Certain fish species prefer certain depths.
Sea Currents/Speed Maps - The location of major currents, as well as, loops and eddies.
Sea Currents/Temperature - The location of major currents, as well as, loops and eddies with temperatures.
Please refer to this link for a detailed explanation of each map provided, as well as selection of further maps of interest. Weather Routing Inc.(WRI) Map Explanations.