1) The document discusses the distribution and chemistry of Earth's oceans. 70% of Earth's surface is covered by oceans, which originally formed as one ocean but are now divided into five major basins.
2) It also describes ocean temperatures, currents, and how thermal and saline gradients drive global ocean circulation. Surface currents are wind-driven while deep currents are driven by water density from temperature and salt content.
3) The water and carbon cycles are interconnected as oceans absorb carbon dioxide from the atmosphere, regulating Earth's climate over long timescales. Chemical and physical weathering processes interact with oceans to shape the lithosphere.