Over 50% of Earth's oxygen is produced by the ocean.
Why it is true
Marine plankton, seaweed and other photosynthetic organisms produce more than half of the world's oxygen, according to the National Oceanic Service.
Source: National Oceanic Service
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.
Related facts
The Darvaza gas crater, known as the 'Door to Hell', has been burning for over 50 years.
In the Bay of Fundy, in Canada, the difference between high and low tide can exceed 15 metres.
Coral reefs cover less than one percent of the ocean floor but support twenty-five percent of all marine species.
The Amazon is not the true lung of the planet.
