As divers, we spend a lot of time in the sea, or at the very least a lot of time dreaming about it. The more we know, the more we can protect and enjoy the oceans. With that in mind, I’ve gathered the following 16 facts, some of which I knew, and some that I only learned while researching this article. Set your memory to “record” and read on to find out 16 things nobody knows about the ocean.

Sixteen Things Nobody Knows About the Ocean

1. Challenger Deep, the deepest known part of the ocean at 35,814 feet, is named after the HMS Challenger. This British Naval survey ship undertook the first-ever global marine-research expedition.

2. The Pacific Ocean has the most coral because reef-building corals can’t tolerate waters under 64.4 F (18 C). The Pacific also boasts a larger surface area than all dry land put together. It contains just over 50 percent of all oceanic water. It’s shrinking at just over an inch a year, though, due to the effects of plate tectonics. So maybe in a few billion years, I’ll need to change this article to say that the Atlantic is the biggest ocean.

3. The Pacific Ocean gets its name from Ferdinand Magellan. He called it Mar Pacifico in Portuguese, meaning “peaceful sea.” Ancient Greeks named the Atlantic Ocean for Atlas, the mythological Titan who held the world on his shoulders.

4. Anchialine pools are landlocked bodies of water with subterranean connections to the oceans. These pools are very common throughout the world, but are especially common on the Big Island of Hawaii, as well as in Mexico’s Yucatan Peninsula, where they’re known as cenotes.

5. The longest mountain range on our planet is 90 percent underwater. It contains the highest number of active volcanoes. Called the mid-ocean ridge, this chain of mountains runs for over 40,000 miles along the planet’s tectonic plates. If you think of the planet as a baseball, this ridge would be the stitching.

6. The term “global sea level” actually represents an average, and doesn’t mean that the oceans are all at one level. Sea level can vary around the world even if we take out such factors as tides, rain and melt water. For example, the West Coast of the United States has a higher sea level than the East Coast.

7. The novel Wide Sargasso Sea by Jean Rhys actually has nothing to do with the Sargasso Sea. Named after Sargassum seaweed, this large area of water in the North Atlantic is also, sadly, home to the North Atlantic garbage patch. This is made up of non-biodegradable plastic, which is trapped here due to ocean currents.

8. Seawater contains gold. It holds a lot less than was previously thought, but at around 16,500 tons, using the conservative estimate, it’s still a lot of gold. But as that equates to around 10g/km³ don’t expect anyone to get rich quick off it just yet.

9. The Census of Marine Life currently estimates that there are around 250,000 species of marine life recorded, excluding microbes. Scientists have yet to describe another 750,000. Some scientists think this number to be much higher. If we include microbial life, it could be in the billions.

10. Had things gone to plan, the Titanic would have arrived in New York one week after leaving Southampton. A dolphin would take 103 hours and 49 minutes to cover the same distance at top speed. The average human swimmer would take 1,139 hours and 48 minutes. The Atlantic sailfish, the fastest fish in the ocean, would blow away the competition, completing the distance in 45 hours and 35 minutes if traveling at its top speed of 75 mph (120 km per hour).

11. Many of us know that leatherback turtles get their name from the fact that, unlike all other sea turtles, they don’t have hard shells. But you may not know that they can grow up to 6 feet long (1.8 m) and weigh almost 1 ton.

12. Though we all think of the ocean as blue, in fact the vast majority of the ocean is black. After 3,280 feet (1,000 meters) virtually no light is available.

13. As the moon’s orbit increases each year by 1.5 inches and its gravitational pull causes tides, over time (millions of years) this effect will wane and the oceans will have no tide.

14. The Arctic Ocean is the smallest ocean, and also has the least salty. If current global-warming trends continue, scientists think that this ocean may be ice-free by 2040 for the first time in human history. The additional fresh water will have major effects on ocean patterns and sea levels.

15. Of marine pollution, 80 percent comes from the land, and 80 percent of this marine debris is plastic. Noise pollution is also increasing, and we’ve yet to see the full extent of the damage this will cause. I’m sure most divers have heard noise pollution on a personal level when dive guides festooned with tank bangers happily tap away on their tanks. (Personal gripe!)

16. My final insight is one that unfortunately not many seem to acknowledge. The ocean belongs to no corporation, government or individual. We are all guests, and we should treat it with respect.

So there you have it, my 16 tidbits about the ocean. Have some of your own to share? Let us know!