Geoid

A geoid is the specific shape that the ocean surface would take under the influence of Earth's gravity and rotation alone, without the effect of winds, tides, or currents. It serves as an imaginary, undulating reference surface representing global mean sea level, extending continuously across continents to establish zero elevation

Via: This is the true shape of our planet, known as GEOID. https://x.com/forallcurious/status/2077968091322163703