Oceanography

The ocean covers 71% of Earth's surface, contains 97% of Earth's water, and produces 50% of the world's oxygen through phytoplankton photosynthesis. Yet over 95% of the ocean remains unexplored. The average ocean depth is 3,688 meters; the deepest point (Challenger Deep) reaches 11,034 meters. Ocean currents act as a global conveyor belt for heat — the Atlantic Meridional Overturning Circulation (AMOC), which keeps Northern Europe warm, is weakening due to climate change. The ocean has absorbed 93% of the excess heat from human emissions and approximately 30% of CO₂ — this warming and acidification is devastating coral reefs and marine ecosystems. Ocean research is constrained by the cost and difficulty of deep-sea operations — ROVs and submersibles can reach the deepest points but remain expensive.