The Pacific Ocean is still a place that occasionally baffles marine biologists when it comes to what lies beneath its surface. The Mariana Trench alone, which is the deepest place on the planet, is still being explored due to its expansive depth. With exploration comes discoveries and usually, they're in the form of some strange creatures that we hadn't known anything about prior to a dive. Some of these are cute and unassuming while others look like they should be starring in a horror film.

The trick to knowing why a species appears the way it does or has certain behaviors is to know about its environment. Many bottom-dwellers and deep-sea creatures must adapt to their dark, often frigid, environments in order to survive. This can mean bioluminescence, long, sensory-proficient legs, or even gargantuan teeth that eviscerate prey before they even know what hits them. A fascinating world lives just beneath this vast ocean and while there's enough sealife for at least 20 of these articles, we're only exploring 25 of the most interesting marine life that graces these waters.

You might find that you've seen or heard about some of these creatures before and others... Well, let's just say they'll haunt your every nightmare. Each one is unique and different and offers something to the Pacific environment that we all know for being so diverse and ever-changing. Some of this sea life has forged its way throughout centuries and adapted to overcome each new change, while others have been recently discovered and are still being studied by Pacific scientists. Go ahead and check out what's really living just beneath that glassy surface.

24 Japanese Spider Crab

If you hadn't guessed by its name, this giant crab calls the cold waters off the coast of Japan its home. They're a loner species, known to hunt solo as they scavenge the bottom of the sea floor for food. They're somewhat of a gentle giant as they're not known hunters and are more likely to lose their own limbs via fishing incidents than to take the limbs off something else. They are a protected species, as their numbers have shown a significant decline in recent years.

23 Vampire Squid

The Pacific is known for having some heft predators but, similar to the last gentle species, the vampire squid won't do much. Interestingly enough, contrary to what its name would imply, it's not a squid at all. This creature has its own unique identification and again, contrary to its name, it doesn't hunt at all but rather preys on scraps in the water surrounding. Its name comes from the extension of its "cape" as well as its deep red color. It also does not have or exude ink but will expel a bioluminescent substance to confuse potential predators.

22 Robust Clubhook Squid

This squid (which is, in fact, of the squid species) is interesting because it spans anywhere from California to Japan and can live in tropical or frigid waters. They can grow to almost seven feet in length which means they can have anywhere from 15 to 18 club hooks. Their sucker count will range anywhere from 50 to 60, making it one of the largest species of squids found in the Pacific Ocean, baring the elusive giant squid which was first photographed in 2004.

21 Goblin Shark

This scary-looking shark lives too far below the surface for anyone other than a diver to have a run-in with it and can exceed depths of 4,000 feet. The only time they'll ever venture near the ocean's surface is to feed, during which they can unhinge their jaws. Interestingly enough, their intimidating teeth is a trademark feature due to the fact that they're the only shark whose teeth won't fully fit in their mouth. They tend to stay out of the way of anything other than the fish and squid they prey on which means they're rarely able to be filmed.

20 Sea Toad

That's right, you'll even find toads on the ocean floor, too! This sea toad is native to deep Pacific waters and is actually part of the anglerfish family. This bottom-dweller can be found at depths of roughly 8,000 feet and the scales you see covering it are actually spines. They grow to about a foot in length and if you look closely enough -- just in front of their dorsal fin -- you'll find a hanging lure that lights up to become a bioluminescent trap for unexpecting fish. Its "legs" are actually fins, giving it the appearance of a strange underwater frog.

19 Frilled Shark

This shark has been around for quite some time and is more akin to a dinosaur than an actual shark. The frilled shark is quite the predator, streaming through the ocean in more of an eel-like fashion than what we're used to seeing with larger sharks. They can grow up to seven feet in length and prefer to lunge and swallow their food whole, despite how large it may be. Their main protein of choice is squid but they'll eat anything substantial, even other sharks.

18 Grenadiers

Otherwise known as rattails (can you see why?), these bottom-dwellers are a species of fish who have adapted to dark and frigid living. They're found near the Arctic and Antarctic and are rather small, topping out at just under four inches in length. They're highly adept for deep-sea life, as they have chemoreceptors and chemosensory barbels to help them tune into potential prey and landmarks. They've been found at depths as deep as nearly 23,000 feet, making them pros at diving and pressurized living.

17 Chimera

The chimera fish is closely related to a shark but is not of the shark species. The fish has earned its name due to its unique features, making it both intimidating yet intriguing to look at. There are several types of chimera, including the Callorhinchus callorynchus, which is pictured above. They live at moderately low depths around 8,500 feet and only grow up to roughly five feet in length. Their oddly-shaped snout is a sensory organ, however, many also have a venomous spine that sits just in front of their dorsal fin.

16 Fringehead

Now, this is one fascinating fish. Called the sarcastic fringehead, this unique species can be found off the coast of California. The behavior depicted in the photo is a display of territorialism, displayed by most males when defending their grounds. More research must be done to learn more about this intriguing fish, but their name certainly suits them -- their dominant nature is what makes them such unique species. The varying colors on their gills as well as the size of their teeth help to decide how successful they are at scaring off other males.

15 Pacific Viperfish

If you want to talk about nightmare fish, the Pacific viperfish is a great place to start. Not only are its teeth too big for its mouth, but they also have luminescent scales that will light up, assumedly to signal to other species in the area that they're around. This may also help to attack smaller fish and crustaceans but that has not yet been confirmed. Not too much is known about these odd deep-sea creatures other than the fact that they're eating machines and will automatically try to swallow anything, regardless of its size.

14 Slender Snipe Eel

Although this looks like some kind of dragon, it's actually of the eel species. The slender snipe eel has a mouth that's very beak-like in structure, making it somewhat monstrous-looking, but serves a practical purpose. Since they prey mostly on crustaceans, a hard beak needed to crack the shells of crabs, lobsters, etc. They don't weigh very much and not much else is known about them, considering the only specimens most scientists have, have been found from the stomach contents of other fish.

13 Humboldt Squid

When it comes to predators to watch out for, the Humboldt squid holds a high reputation in the Pacific. While they're not intentionally aggressive toward humans, there have been reported attacks from researchers and divers. These scary-looking squids are known for their flashing colors as well as their razor-sharp claws, leading up to a beak-like mouth opening. Most Humboldts reach a size of four feet in length and can weigh in at over 100 pounds. Their numbers are actually increasing as a result of their rapid reproduction rate.

12 Giant Squid

The giant squid is different from its cousin, the colossal squid, and is considered to be so massive due to deep-sea gigantism. It can grow up to 43 feet which makes it one of the largest species of animal on earth and while documented sightings are rare, there have been plenty of eye-witness accounts to back this up. What scientist do know is that these squids will use two main tentacles to grab their prey, reel it in, shred it with their "teeth", and pull it toward their beak-like mouth.

11 Graceful Kelp Crab

Hey, we never said that Pacific sea life couldn't be cute, too! This tiny little graceful kelp crab is harmless (as you can tell) and can be found among kelp groves. Its scientific name is pugettia gracilis and doesn't vary much from any other species of crab other than its chosen environment. It can also be found on rocky shores in tidal zones amidst kelp debris. More often than not, these tiny crabs will be found in protected underwater environments where they're free from predators and not likely to be seen easily.

10 Kelp Isopod

This little guy is known as a kelp isopod and it's very similar to a bug that you'd find on land. It has an appearance that's almost like a potato bug (or roly-poly to some people) but thrives in an environment where the kelp is plentiful. It can also be found in tidepools on rocky shores and in mussel beds but will likely remain hidden if it can. These tiny bug-like creatures eat algae and can be found anywhere from the coast of California all the way to Siberia. While their coloring varies, they're all of the same species and are an important part of the Pacific ecosystem.

9 Japanese Skeleton Shrimp

These strange skeleton-like structures are actually a species of shrimp. The Japanese skeleton shrimp is an omnivore and can grow up to two inches in length. They'd be challenging to spot especially due to their changing color, which varies from red, green, or blue depending on where they are in the water. At one point, they were native only to the waters off Japan but have since migrated. They call man-made structures in the water and floating objects their home, which makes them fairly adaptable creatures.

8 The Great White

Many people know about these apex predators and the old saying, "it's more afraid of you than you are of it" simply doesn't apply here. Great whites are eating machines and have rows of teeth that are designed to lock onto prey and tear until the animal is nearly lifeless and immobile. They can grow up to 13 feet in length and are quick swimmers and have a bite force of roughly 4,000 pounds. These are the monsters of the deep in the Pacific and can be merciless and are worthy of respect.

7 Spiny Dogfish

Surprisingly, the spiny dogfish is a species of shark despite its small size. The species of dogfish native to Pacific waters is often referred to as the Pacific spiny dogfish and varies slightly from its cousin species. The danger with this shark lies in its spines rather than its bite, which can be used as a defense mechanism to encourage predators to loosen their bite when attacking. Additionally, they can secrete venom from these spines, making them multifunctional and highly effective.

6 The Dumbo Octopus

This adorable little guy was recently captured on film by a group of scientists who also reveled in its cuteness. While it looks like an extra from Finding Nemo, it's actually called the Dumbo octopus. This is obviously a baby of the larger, more well-known species, of which you can clearly see why the species earned its name. With a large, blob-like body, elongated "ears", and flexible tentacles, this octopus looks like an underwater elephant. It lives in deep waters at a depth of roughly 23,000 feet making it the deepest-diving of any octopus species.

5 Giant Amoeba

In 2011, it was discovered that a species of giant amoeba inhabited the deep waters of the Mariana Trench. Also known as xenophyophores, these single-celled organisms are the largest ever recorded, measuring roughly four inches in length. While they're referred to as amoebas, they're actually more akin to a sponge but are living animals. They were found nearly 6.6 miles under the surface which is also the lowest depth any xenophyophores have ever been discovered... We can't imagine what else scientists will find down there!