Vertical Datum references a tidal datum (MLLW)...for more information see Tides and Currents.
For more information on your flood risk go to www.floodsmart.gov.
FEMA's National Flood Hazard Layers not showing?
Why aren't the FEMA National Flood Hazard Layers showing on the ESRI Map?Possible reasons:
Note: Your zoom level may have changed. ESRI's zoom levels must be between 14 and 16 to show National Flood Hazard layers.
Latitude: 32.033333° N,
Longitude: 80.901667° W,