Mountain ranges and land ice have "extra" gravity that has a very large effect on sea level. Antarctica has so much ice, it pushes the land down almost 1/2 mile, and the sea level south of the equator is something like 8,000+ feet higher. The oblate spheroid of our planet (because of it rotating on its axis) is "sagging" southward. Here's an article that explains it:
https://www.npr.org/templates/story/...toryId=9428163
Because water expands as it warms, this spreads it out over a greater area, so the mass on any given spot is slightly less.