Mostly differences in the geoid [1]. The planet isn't perfectly round, and gravity varies quite a lot [2]. There are other factors, such as the cold/warm water

Mostly differences in the geoid [1]. The planet isn't perfectly round, and gravity varies quite a lot [2]. There are other factors, such as the cold/warm water cycle creating very slow currents that push water towards certain landmasses. But as I understand it, gravity is the main cause. [1] https://en.wikipedia.org/wiki/Geoid https://en.wikipedia.org/wiki/Geoid [2] http://e360.yale.edu/feature/the_secret_of_sea_level_rise_it_will_vary_greatly_by_region/2255/ http://e360.yale.edu/feature/the_secret_of_sea_level_rise_it...