Subnautica is an open-world action-adventure game, where players have to survive the deep oceans on an alien planet. Everyone knows that our planet's oceans are filled with uncovered secrets and mysteries. But for the creators of Subnautica, that wasn't enough, so they introduced the terrifying underwater ecosystem of planet Aurora.

RELATED: 10 Things You Didn't Know You Could Do In Subnautica

Some creatures are mesmerizing, some are breathtakingly beautiful, some are even adorable, but most are either scary or just unsettling. A lot of these alien lifeforms might look disturbing for players, leaving them uncomfortable just looking at it. For this list, we've gathered all Subnautica creatures that make the hair stand up on every players' backs, and ranked them according to their actual strength.

10 Peeper

While in general a harmless creature, the Peeper sure has a way into people's nightmares. Scopophobia is the fear of being stared at. Players who didn't know what it was, or thought they don't have this disorder, now realize, that they indeed have scopophobia.

Unfortunately, Subnautica is full of creatures whose only purpose is to stare deep into every players' soul, and they're literally everywhere. If it's not the Peeper, it's Eyeye, and even though they're small and harmless, people want to slay them all. Every gaming forum that asks the question "which Subnautica creature gives you the creeps" gets an overwhelming wave of responses saying the Peeper.

9 Eyeye

Another passive creature that can dive deep into the subconscious of players, the Eyeye is harmless in the game, but attacks the player on a deep level, unlocking once again, the unknown fear of being constantly stared at.

RELATED: 10 Horror Games That Are Scary Without Relying On Gore

If people thought a toddler can stare into their souls, they haven't been face-to-face with this adorable nightmare. And to make things worst, the Eyeye is found almost everywhere on the map, so it's basically unavoidable. Future Subnautica players, get ready to be stared at.

8 Bleeder

The Bleeder is the most annoying creature in Subnautica bar none. It has minimal health, so it's easily killed, but it's very relentless, highly aggressive, and if a player doesn't notice it clinging to their body, it can cause quite a bit of damage.

RELATED: 10 Pro Tips For Subnautica You Need To Know

This little creature causes some sort of PTSD in players, as they say, that after learning what they're capable of, even seeing one from a distance causes irritation and fear. The number one task when starting this game is to avoid these leeches.

7 Warper

The Warper is one of the creepiest creatures as told by most players, because of its unusual and highly unsettling look. In fact, it's not even a creature, rather a biomechanical life form created by the Precursor race.  Even though it only attacks when provoked, it can cause damage between levels 10 and 69, so it's better to not take those chances.

It has the ability to generate a teleportation gate, and they're not shy about using it. Some say the Warper is to Subnautica, what the Enderman is to Minecraft. And this analogy isn't that far off, as both cause high damage, and relentlessly attack when provoked. Not to mention, that both of them are creepy looking.

6 Sand Shark

The Sand Shark, as can be assumed by its name, is always near the seafloor, and never goes near the surface. It's an aggressive predator, but its looks are much scarier than its actual damage rates. It has four eyes, a huge fin on top of its head, and a lot of teeth. A scary amount of teeth. And for some reason, it always looks like it's smiling which makes it even creepier.

But besides all of these horrifying qualities, it's not that hard to beat. Its bite is only at a level 30 damage, and its health is at a low 250. Although it's faster than some, it can be defeated if players aren't too startled by the sight of this monster.

5 Crabsquid

People either find the Crabsquid magical, ridiculous, or plain terrifying. But even if some can't take its absurd exterior seriously, they should avoid it, because it is very aggressive, and has a decent damage level to be scared of.

RELATED: The Best And Worst Alien Video Games

That said, its health is not that high, so this creature is one of the easier to defeat. But keep in mind, that they're also capable of temporarily disabling electronics. It is one of the most alien-looking creatures of the game, reminding the player once again, that they're far from home.

4 Sea Treader

The Sea Treader is not an aggressive creature, but very defensive. They're mesmerizing, colorful, but players shouldn't go closer, because when threatened, these beasts have very high damage levels using their ginormous legs.

The Sea Treaders move in herds, and they're active day and night. For some, they're beautiful creatures resembling AT-ATs, but all the arachnophobes out there should steer clear of these giants, as they do resemble giant spiders, and can look very overwhelming up close, with their skeleton-like face and pitch-black eyes.

3 Ghost Leviathan

The Ghost Leviathan is highly dangerous even in its juvenile state. With a damage level of 84, this beast is one of the most dangerous in the game. They're the giants of predators, with only one being bigger, the Sea Dragon Leviathan.

At first glance, they may seem transparent, but under that glowing exterior, players can see a massive bulk of pure muscle. These monsters lurk all around the map, as they're not picky about their surroundings. And as mesmerizing they may seem, players should not go take a closer look, as they can easily kill anything in one or two bites. So if anyone is feeling adventurous, they should make sure to have enough health to survive a bite of over eighty points.

2 Sea Dragon Leviathan

The Sea Dragon Leviathan is the largest predator in the entire game. If anyone is scared of aggressive giants, this would be on the top of the list. There are only a total of three of them all around the map, two in the Inactive Lava Zone, and one in the Lava Lakes.

They are relentless hunters, they spit fire, and the cherry on top is their ability to instantly kill a player with just one bite. The only reason they're not on the top of the list is that they're easily predictable due to the fact that they always live in the same two places, and they're relatively slow. Also, once a player experiences the horror that is the Reaper, they'll fast miss the days of battling the Sea Dragon.

1 Reaper Leviathan

The sole existence of the Reaper makes this game almost a horror game. Creators used sounds, dreadful looks, not to mention horrifying jump scares to bring the most out of this beast, and players jump out of their seats simply by the anticipation of the behemoth. There's only one thing to do when encountering this monster, and that's to swim. If it catches the player, death is inevitable.

Even hearing its sound makes players' skin tingle in anticipation, and after turning off all lights and being motionless, some might think they successfully avoided the attack using stealth. Just wait until they turn their lights back on. This creature is the definition of scary when it comes to this game, and any player who knows just how scary it is can have nightmares revolving around just the signature sound it makes.

NEXT: The 10 Best Survival Horror Games Of All Time, Ranked According To Metacritic