That doesn't make sense. Actual sea level differs from mean sea level because of the tides, not because of some gravity anomaly. Remove those tidal effects in one way or another (three ways; see my previous post) and what will be left is some form of mean sea level. The geoid, at least over the oceans, *is* the surface corresponding to mean sea level.The diagram show a section of varying sea floor and the water column above it. The proposal is that where the sea-floor is above mean sea-floor level the actual sea level is below mean sea level.
I think that's a trifle harsh.That doesn't make sense.