From the ancient Greeks to the violent Vikings and even present-day local fishermen: tales about sea monsters have been a part of human culture for as long as we can remember. Back in the days, these tales were largely inspired by a fear of the unknown. Today we know a lot more about these ‘monsters’, but much of the fear remains. Are those fears rational? How scary are these sea monsters really?

I asked my insta fam which ocean creatures they fear the most. Turns out there are too many to discuss in one single blog, so I decided to spread it out over multiple blogs. Welcome to episode 1 of the Scary Sea Monster Series!


The honor of most frequently mentioned sea monster goes to the titan triggerfish. The triggerfish may be relatively unknown to non-divers, but I’m pretty sure every diver has heard one or two horror stories about this feisty fish. They don’t really look that terrifying: they’re actually quite beautiful and not very big. But what the titan triggerfish lacks in size, he makes up in temperament: it’s not uncommon to see one chase after a stressed-out diver. Usually it will stay at that, but occasionally it attacks and bites. The bite of a titan triggerfish is no joke: it can cause a mean bruise or infection, or a few holes in your fins if you’re lucky.

Despite their notorious reputation, most encounters with titan triggerfish are peaceful. But they tend to get very protective – and sometimes aggressive – when you enter their territory. This happens especially (but not only) during their mating season in April/May, when they protect their nests. So how do you know when you’re in trouble? When triggerfish attack, they turn on their side and rotate their eyes in a freaky way before charging at you. That’s basically your cue to get the hell out of there.

The titan triggerfish is a nightmare of many scuba divers
Photo by Zsispeo

What to do if you see a titan triggerfish

Titan triggerfish are very common in the Indo-Pacific and Egypt: I see them on at least 75% of my dives here in the Philippines. So knowing what to do when one decides to come after you might just come in handy! You basically approach a titan triggerfish the same way you’d approach a creepy guy on the street at night: you cross the street and pray he didn’t see you. In the unfortunate event that a triggerfish decides to come after you, the best thing you can do is to swim away backwards and horizontally. Make sure your fins stay between you and the little devil. Holes in your fins may not be what you want, but it’s still preferable to holes in your legs. The territory of a triggerfish expands upwards in a cone shape, so whatever you do: don’t swim up!

Another thing you can try is to scare him away by purging your alternate air source at him. Remember that an aggressive triggerfish is just trying to protect its nest, so please don’t use brute force to protect yourself. Just get out of its territory and be more careful next time.

Edit: after publishing this blog a friend and fellow instructor suggested to shine a torch at an aggressive triggerfish, apparently they hate it!

How scary are they really?

Let’s take a look at the facts: titan triggerfish are aggressive and can leave serious injury or bite marks in your dive equipment. However, I’ve never heard of a triggerfish actually killing anyone (perhaps from a heart attack, but not from the bite itself). They are very common in South-East Asia and Egypt, but they tend to mind their own business unless you enter their territory. They show aggressive behavior primarily during their mating season. In the hundreds of dives I’ve made throughout Asia, I can count the times I’ve been chased by a triggerfish on one hand. When it did happen, I wasn’t really paying attention to my environment and suddenly found myself staring a triggerfish in the eye. So is our fear of triggerfish rational? Yes, but I’d say an attack is often also avoidable.


Jellyfish are thought to be the oldest creatures on the planet: they pre-date dinosaurs by millions of years! Where most (if not all?) animals have gone through a natural evolution, jellyfish apparently feel perfect just the way they are, because they barely changed at all in the 500 million years they’ve inhabited our earth.

Jellyfish aren’t actually fish: in order to qualify as a fish, you need to have gills to breathe and fins to swim, among other things. Jellyfish have no backbone and absorb oxygen through membranes. They also don’t have a heart (first warning sign), brain, blood or eyes – and their mouth doubles as an anus (…). The Australian box jellyfish is considered the most venomous creature inhabiting our oceans: its venom can kill a human within minutes. Another type of jellyfish, the immortal jellyfish, is – you guessed it – immortal. When it ages or gets harmed, it can transform itself back into a polyp, after which it produces new and genetically identical jellyfish.

In case you’re not freaked out yet: there have been reports of ‘jellyfish gone wild’ from all over the world. In 1999 they left 40 million people in the Philippines without power by clogging the cooling pipes of a power plant. They’ve partially disabled an aircraft and were responsible for sinking a ten-ton fishing trawler. They’ve invaded nuclear power plants. And they win Nobel Prizes. 

How to protect yourself from jellyfish

Jellyfish are everywhere: from the ocean bottom to the surface and from tropical waters to the Arctic. Luckily for us, most of them are harmless. Even if you get stung it will most likely be painful, but not dangerous. Considering the size of our ocean, an encounter with a truly nasty jelly is pretty rare. But that doesn’t mean it can’t happen, and therefore you should be taking precautions.

First of all, if you know that a certain area is often frequented by (venomous) jellyfish, simply avoid swimming or diving there. Many jellyfish are hard to see because of their transparent body, so most people don’t realize a jellyfish is nearby until they experience a sting. Therefore a good way to protect yourself is to wear exposure protection when you go diving. And always make sure there is a jellyfish first aid kit at hand.

If you or someone else got stung, you need to determine if the sting is potentially dangerous. If you experience an extreme rash, difficulty breathing, nausea, dizziness, or changes in consciousness, it’s time to seek professional medical care. To administer first aid, rinse the area with vinegar or a commercial spray and remove the tentacles. After that, soak the affected area in hot water. And no, do not pee on it.

*These are just a few examples of possible ways to treat a jellyfish sting and are not meant as medical advice. When in doubt, always seek professional medical care. 

How scary are they really?

How rational is our fear of jellyfish? Let’s see: most jellyfish species are harmless. Their stings are usually painful, but not deadly. However, certain species can kill a human within minutes. Many of them are (more or less) invisible. One type of jellies is immortal. They’ve been around for 500 million years. And they are clearly taking over the world. My advice? Take a deep bow for these senior citizens and stay the hell away from them.


I say sea snakes, but what most people actually mean when they refer to a snake snake (in the context of scary marine creatures) is the banded sea krait. Apparently they are not true sea snakes, but I’m not a marine biologist so I won’t get upset if you call them that anyway.

Banded sea kraits are amphibious, which means that they live both on land and in sea. They come to land to lay eggs and rest, but hunt in the ocean (mostly at night). Their body has a striped pattern of alternating bands of black with grey or white – hence the name. The end of their tail is flat – much like a paddle – which allows them to swim around. They are found throughout the Eastern Indian and Western Pacific Ocean, mostly along the coast on coral reefs.

The banded sea krait has the strongest venom of all snakes
Photo by Bernard Dupont

Banded sea kraits have the strongest venom of all snakes: it’s ten times more powerful than that of a rattlesnake. A bite from a sea krait can result in convulsions, paralysis, heart failure, or death. That sounds like 4 good reasons to be scared of them, but sea krait attacks on humans are actually extremely rare. They are not aggressive at all, even when provoked (although I wouldn’t recommend it). There are a few reports of attacks in the past, but these are almost exclusively from fishermen that had accidentally caught one in a fishing net.

What to do if you see a sea snake (banded sea krait)?

Just like the titan triggerfish, banded sea kraits are very common in Asia; I see them regularly when diving. So what to do when you suddenly find yourself near a sea krait? The answer to that question is fairly simple: you do nothing. As long as you mind your own business, the sea krait will do the same.

How scary are they really?

Despite their extremely potent venom that could easily kill a human, I’m not worried about banded sea kraits at all. There seems to be a myth that the mouth of a sea krait isn’t wide enough to bite a human, but that is not true. They can swallow an eel whole, so I’m pretty sure biting a human wouldn’t be a problem. However, they simply choose not to! So the next time you see a banded sea krait just relax, admire its beauty, maybe resist the urge to pull its tail, and move on with your life.

That’s it for the first episode of the Scary Sea Monster Series! In the next episode, I’ll discuss 3 new monsters and if they’re really that scary. Which terrifying ocean creature do you think should make it on this list?

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