While underwater water doesn't seem possible, the "river" is actually a briny mix of salt water and hydrogen sulfide. It's much more dense than regular salt water, so it sinks to the bottom and forms a distinct separation that acts and flows like a river.

Anatoly Beloshchin

In addition to giving scuba divers the distinct feeling that they're flying through a landscape painting, the underwater river allows them to snap mind-blowing pictures like the series you're looking at taken by Anatoly Beloshchin.

Anatoly Beloshchin

Unfortunately, hydrogen sulfide is extremely toxic, so the chances of the above scuba diver pulling in some sort of meta-fish aren't great. However, there is an underwater body of water on the abyssal plain (the part out past the continental shelf where the ocean floor starts to make s**t real) that is teeming with life. Deep sea lakes look like normal lakes, complete with sandy and rocky shores. Scientist call these lakes "cold seeps," but they're a hotbed for life, because apparently waterfront real estate is a hot commodity under water, too. The "rocky" shores are actually made up of hundreds of thousands of mussels.

Blue Earth via Youtube

Even weirder, the lakes under the waves have waves of their own. Check out this video of scientists discovering the waves for the first time if you want to see something cool and hear what it sounds like when scientists lose their s**t.

You've likely seen aerial shots of these dark blue holes and assumed there was something down there accounting for the darkness. Maybe some silt or seaweed that's collected in a crater on the sea floor. In fact, those are giant sinkholes in the middle of the ocean that formed during the Ice Age the same way giant city-block-sized sinkholes form in cities today: water, chemicals, time and bureaucratic mismanagement.

horslips5

Of course, it's not totally fair to compare it to the Guatemala sinkhole that swallowed an entire city block, since it's bigger and three times deeper than that. Notice that sharp contrast from bright aquamarine to deep dark blue? That's not caused by anything dark trapped in the sinkhole. It isn't caused by anything. It's hundreds of feet of absolutely nothing but cold water straight down to whatever is below the bottom of the ocean until presumably it starts warming up as you near the center of the earth.

USGS

If you're the sort of person who immediately wants to know what the craziest goddamned thing you can do to a 600-foot ocean bottom sinkhole is, world free diving champion Guillaume Nery has you covered. He stood on the edge of the world's deepest blue hole without any sort of breathing apparatus, ignored every fiber of his being telling him he was perched on the mouth of a sarlacc and decided he wanted to touch the drain in the ocean's deep end.

Guillaume Nery, Youtube

And it only gets eerier inside the hole, where you're forced to face the reality that you've stumbled into either a) the lair of something terrible that is going to swim by overhead and blot out the last trace of sunlight you'll ever see or b) the stomach of some sort of ocean bottom Venus flytrap designed specifically to trap and digest people who see something beautiful and feel the desire to swim down its throat.

Jenny Huang, Dive Photo Guide

The diving bell spider is the only spider on earth that spends almost its entire life underwater. It weaves a special bell-shaped web that catches and contains air bubbles that it brings down from the surface. The web acts like a fish's gills and filters oxygen out of the water around it, so the spider can stay under for a day or more at a time before needing to get more bubbles. It carries the bubbles down to its web by trapping them in hairs on its abdomen, as seen in this not at all terrifying picture from the New York Times:

The New York Times

The spider then takes this air bubble and transfers it over to its web, where it can lie in wait for its prey, avoiding the predatory birds above the water's surface and any pockets of your nightmares that used to be spider-free.

BBC Nature

Here's a video of one bringing the bubbles down before finally climbing inside and beginning to devour a freshly caught snack.

The female diving bell spiders often construct much larger webs so that they can house their eggs.

Getty

And now you get to worry that the squishy thing you just stepped on was a nest of hatching spiders.

Some underwater kelp forests are so tall and dense that they resemble tree cover. These kelp forests exist all over the world and host a vast array of life. They can grow at depths up to 150 feet and still reach the surface. This giant kelp can grow up to two feet in a day, which would be the most terrifying thing in the world if it happened on land.

Timothy G. Laman, National Geographic

Carindale Research Lab

But kelp forests are still just underwater plants doing what underwater plants do. What would be really cool is if there were a normal forest that was underwater. But that could never happen because trees need oxygen, and therefore can't grow underwater.

Triton Logging

But, sometimes when hydroelectric dams are built, entire forests are plunged underwater. That robot, named Sawfish, has been made to harvest cedar, pine, spruce and Douglas fir from water 200 feet deep. It's an unmanned submarine that is controlled remotely from the surface. It attaches airbags to the trunk of the tree, chainsaws it and then releases the trunk so it can float to the surface. Before you say "Look at the cute little robot cutting saplings," know that those are full-size trees and that robot is pretty damn big.

Treehugger

But you knew that. You've seen birds dive into the ocean before, at which point you assume that they bob back to the surface, shake the water off their feathers and get back to flying. They're not spiders after all, right?

Paul Osmond

See, the gannet has a couple adaptations that allow it to dive from heights up to 100 feet: It has bubble-wrap-like air sacs in its chest that allow it to survive impacts that bridge jumpers count on being the quick and easy way out, and it has no external nostrils. You might think that's a weird feature for a bird to need, but that's because you never dropped a cool buck fifty on nostril pincher things that swimmers use. Gannets can be found 72 feet under the surface of the ocean, swimming with their wings and feet and confusing the hell out of some sharks.

Jason Heller/Barcroft Media, Telegraph

Then there's the dipper, which gets its name for the way it sticks its head into shallow water and scans for prey. Aw, just like a duck or a goose! And then it "dips" the rest of its top half into the water and starts swimming around for a couple of minutes like it ain't no thang. Nothing dramatic. One second, it's flying through the air, the next it's bobbing around on the surface, then it spots something and plunges in and swims by flapping its wings like it is flying again, but this time underwater.

Seeing them in action makes you almost want to accuse them of cheating at evolution. Y'know, if that didn't sound retarded.

National Geographic, via YouTube

You can find more from Kier at makeshiftcoma.blogspot.com

For more insane finds, check out 6 Insane Discoveries That Science Can't Explain and 6 Mind-Blowing Discoveries Made Using Google Earth.

Imagine being trapped aboard the doomed Titanic on an icy Atlantic. . . with the walking dead. Check out Chris Pauls and Matt Solomon's Deck Z: The Titanic.