About half of Earth’s oxygen production happens in the ocean.
Much of the world’s oxygen production comes from tiny organisms near the ocean surface.
Photosynthetic organisms in the ocean, including algae and some bacteria, release oxygen as they use sunlight to make food. NOAA estimates that the ocean accounts for about half of Earth’s oxygen production.
Respiration and decomposition in the ocean consume roughly as much oxygen as marine organisms produce. The oxygen in the atmosphere has accumulated over hundreds of millions of years.