Hi I'm Elliot, this is Mental Floss video and today I'm gonna talk about some misconceptions about the ocean. You think you know what's going on with the ocean, but you have no idea.

Misconception #1: The saltiness in seawater is essentially table salt.
So the water in the ocean is very salty but it's not composed as if someone just dumped a bunch of table salt into it. Basically, it's considered salt water because it contains a bunch of minerals that come from the Earth's surface. Rain and snow pick up minerals from the ground, which turns into runoff that goes into the ocean. So, seawater has a lot of sodium and chlorine in it, but, it also has a bunch of sulfates, magnesium, calcium, and potassium. And, because the definition for salt is so vague, these can all qualify. 

Misconception #2: The ocean gets progressively deeper towards the middle.
Much like the land on earth, the surface of the ocean is not consistent. It has its equivalent of mountains and canyons and flat plains. The ocean contains trenches which is the word scientists use to describe the deepest part. And these are [forming plates meet??] which often means that one of the plates moves further down, causing the trench to emerge. One example of this is Mariana Trench, which is about 1,000 mi away from Japan and its deepest point is around 36,000 ft.

Misconception #3: An undertow can pull a person underwater and hold them there.
Let me start by saying that people often confuse undertow with rip current. So the undertow is basically a current near the shore that helps keep the water flow consistent as the waves crash, and, unlike the undertow, rip currents aren't always present but they're a stronger current that pulls away from the shore. Neither undertows nor rip currents can pull a person underwater and drown them. Though rip currents are the ones that pull swimmers far away from the shore, then, people struggle to get back to shore and that can be dangerous and result in drowning. 

Misconception #4: There are not huge waves far away from shore. People typically only see big waves close to the shore so they assume that's not a problem in the open ocean, but, there are rogue waves which can be a major problem in the middle of the ocean. In order to be considered a rogue wave, the wave must be over twice "significant wave height," which is basically the mean of the tallest waves in a given area. In 1995, a rogue wave was reported 84 ft and this can be a major problem for boats, including huge ocean liners - have fun on your next cruise guys. *thumbs up*

Misconception #5: Icebergs are made of salt water.
An iceberg is a chunk of ice that floats in the water after separating from a larger piece of land-based ice. And they're not made up of salt water; they're actually fresh water. That actually makes sense if you think about it because icebergs come from land ice, so they're basically compacted snow, which is fresh water.

Misconception #6: The ocean appears blue because it's reflecting the sky. 
No. It's not reflecting the color of the blue sky it's actually absorbing it. Basically the ocean is continually being hit by sunlight, and, as you probably know, that happens in the form of waves, which contain a whole spectrum of color. The ocean typically absorbs the red wavelengths quicker. The blue wavelengths head deeper into the ocean, then, they get scattered and re-emitted from within the ocean, and that's how our eyes take them in. So to us, the ocean appears blue. *whispers* It's not. It's all different colors.

Misconception #7: We could explore the deepest parts of the ocean.
So you may know that we've only explored less than 5% of the ocean, but many people think that's because of a lack of interest. ...No way guys, it's super interesting down there, okay? The truth is, we just don't have the technology needed in order to explore it. Scientists are trying to develop something known as the 'Sea Orbiter,' which would basically be a space station for the ocean. It could make more ocean exploration possible, but it still being developed.

Alright, let's finish up with some misconceptions about marine animals. *leans to fish tank* Are you excited? ...they're not real

Misconception #8: Corals are mineral deposits. Or fossils. Or rocks. 
People still find it hard to believe that coral reefs are made up of marine animals. So what happens is corals attach their exoskeletons to objects underwater like rocks, or even shipwrecks. They actually have tentacles so they're able to catch fish and plankton to eat. They might not look like animals, but they are. Please, treat them respectfully.

Misconception #9: A porpoise is the same as a dolphin.
Guys, dolphins and porpoises are different animals and they're getting tired of hearing otherwise. There are a few differences. Dolphins have longer beaks and more curved dorsal fins and porpoises are usually a little larger and make less noise than dolphins do. But, they're both members of the cetacean family and they're both intelligent mammals who live underwater.

Misconception #10: Whales spray water from their blowholes.
Just like dolphins and porpoises, whales are members of the cetacean family, so they're also mammals who need to breathe air and they do that through a blow hole on the top of their heads. Once they inhale air through their blowhole, most whales can hold their breath for over an hour, but eventually they need to exhale. When they come above the surface to do that it often looks like they're blowing out water. What they're really blowing out is most warm air - it's warm because it's been inside of a huge warm body - and the air outside is usually way cooler than the air that's being exhaled so it condenses and looks like water, but, a whale is primarily inhaling and exhaling air like any mammal does. Oh, and they also exhale mucus. Lots, and just....lots of mucus.

Thanks for watching Misconceptions on Mental Floss video. If you have a topic for an upcoming misconceptions episode that you would like to see, let us know what it is in the comments below and I'll check it out and I'll see you next week. Bye.