I have found two sites that do Google Maps overlays of sea level rises
Flood Maps
This site allows you to pick a level between +1m and +14m and it overlays a light blue shading for areas below the level you pick, it has a fairly fine resolution.
Sea Level Rise Explorer
This site overlays colours indicating levels above sea level from +1m to +70m (which represents an estimate of the sea level rise if all the ice on the planet melts, something that would take generations). This overlay appears to have a resolution of about 1 sq Km.