How are we ever going to understand our planet if we donít understand the ocean? Sylvia Earle. It covers 70% of the Earth's surface, holds 90% of its living space and half of its species. Imagine vast continents of rainforests and canyons and prairies that lie underwater just waiting to be explored! ONWARD AND DOWNWARD! That's the catchiest slogan I've heard this entire election year. Sylvia Earle.