Shallow sandbars will appear glassy. These are conditions when colors may not be apparent. Mooring buoys are located in the Florida Keys National Marine Sanctuary to keep boaters from damaging coral with their anchors. Some mooring buoys are located near extremely shallow reefs. Do not attempt to motor across a reef to reach a mooring buoy.
Polarized sunglasses are very helpful in distinguishing water colors.
NOAA navigation charts are available at many marine supply stores throughout the Keys.