The List: For World Oceans Day, 10 salty facts

Today is World Oceans Day.

Most of the Earth is covered by oceans, but these bodies of water and the lives in them are far from safe.

Overfishing, plastic waste and the effects of climate change are only some of the ways the oceans are in trouble. So it’s important to understand the seas around us.

1. One ocean: Although people have given names to certain areas such as the Pacific and Atlantic, the world is really covered by one huge ocean.

2. Mostly water: Seventyone percent of Earth is covered by ocean. The Pacific covers 30 percent and the Atlantic 21 percent. Some 97 percent of all water on Earth is in the ocean.

3. Deep: The Mariana Trench in the western Pacific is 36,000 feet deep, easily the deepest place on the planet.

4. High: Dormant volcano Mauna Kea in Hawaii rises 33,474 feet from the ocean floor, but only 13,680 feet are above sea level.

5. The Gulf: The Gulf of Mexico is considered a sea of the Atlantic Ocean.

6. Life: Though hundreds of thousands of forms of oceanic life have been discovered, the real numbers are probably in the millions. Scientists believe all of life started in the ocean. Venus and Mars once had oceans, as well.

7. Largest: The blue whale is the largest life form to live on this planet. That includes dinosaurs. Its heart is the size of a Volkswagen, says savethesea.org.

8. Junk: Excluding other forms of junk, humans leave 640,000 tons of fishing gear in the oceans each year. Marine life can become tangled or swallow the garbage.

9. Bleaching: Coral reefs are bleaching, which can cause them to die. When coral reefs undergo changes in temperature, light or nutrients, they expel the algae that lives in their tissues, which makes them turn totally white. Some 90 percent of Australia’s Great Barrier Reef has suffered bleaching.

10. Plastic: Plastic waste that finds its way into the ocean kills 1 million sea birds and 100,000 marine mammals a year.