It’s often said we know more about the moon than we do about the deals of the ocean. There is a lot we don’t know about the H2O that converse much of the planet. Now we’re getting closer, although, to an important understanding: Just how deep are the oceans, and what’s the volumeter of all that water? The latest, best estimate is 1.332 billion cubic kilometres, according to research pushed in the journal Oceanography. That’s actually lower than former estimates by about five Gulf of Mexico’s.