The 10 Deadliest Creatures You’ll Find in the Ocean

More than 70% of the Earth’s surface is covered by water, and the majority of this comes from our oceans and seas. In fact, the Pacific Ocean takes up more than a third of the planet’s surface.


There are more than a million different species of creatures that call the call the ocean their home, whilst scientists estimate there are 9 million more species that are yet to be discovered.


The ocean can be a pretty dangerous place to live, and that’s because some of the most deadly of creatures live there. From the poisonous to the just outright vicious, here’s a look at ten of the most deadly creatures you may encounter in the ocean.



Whilst pufferfish may look harmless, they’re actually pretty dangerous due to the amount of tetrodotoxin they contain. This is a substance which makes them lethal for fish to eat.


It’s not just fish that should be worried: one pufferfish can carry enough toxin to kill 30 adults, and is believed to be 1,200 times more lethal than cyanide.


Blue-ringed octopus

Found in the waters of Australia and Japan, the blue-ringed octopus is as dangerous as it is spectacular.


When provoked, this tiny octopus will start flashing a bright, neon blue. Whilst it may be a dazzling sight, one bite can kill a human. The pufferfish has nothing on the blue-ringed octopus, as its venom is 10,000 more lethal than cyanide and there is no known antidote.



The stonefish has the incredible ability of being able to disguise itself as rocky seafloor, and is able to grow up to 40cm long.


With venomous sacs on each of its 13 spines, if you come in close contact with a stonefish there’s no way of avoiding getting stung. Despite this, their venom is not used to catch prey. Instead, they will wait for unsuspecting prey to appear and quickly attack them.


Great white shark

Thanks to the Steven Spielberg movie Jaws, the great white shark gets a bit of a bad rep. Humans are not their preferred prey, but they are still pretty dangerous and have been responsible for a large number of unprovoked attacks.


The great white shark sits comfortably near the top of the food chain, where a single bite from their sharp teeth can be fatal.



The lionfish is known for its many spiky fin rays, which also happen to be highly venomous.


Found in the Caribbean and Eastern Atlantic Oceans, the lionfish packs a powerful sting if disturbed. The sting might not be fatal for humans, but it’ll certainly be painful.


Box jellyfish

Accountable for more human fatalities on the Australian continent than sharks, the box jellyfish is one of the most ferocious creatures to roam the ocean.


A sting from a box jellyfish will be extremely uncomfortable and can, in some cases, even be fatal to humans. These jellyfish lure their prey of small fish with their tentacles, readying them for a deadly sting.


Tiger sharks

The tiger shark can reach a length of 5m, making it a relatively large predator of the seas.


Feasting on a diet of seals, squid, birds, and turtles, the tiger shark has a highly varied diet, therefore making it a deadly threat. You can see our sand tiger sharks at our Underwater Shark Tunnel.


Sea snakes

Found in the Indian and Pacific Oceans, there are around 50 different species of sea snakes.


The most poisonous species is the beaked sea snake, whose venom is eight times as toxic as a cobra’s. Just 1.5 milligrams of its venom could kill up to eight humans. Luckily, they are not known to attack humans often – just don’t provoke them.



Stingrays are known for their passive behaviour, and won’t usually attack. Most reported cases happen when divers or swimmers accidently step on them.


When threatened, the stinger in the stingray’s tail will whip up. Contact with the stinger will usually cause pain and possible infection. More serious attacks are rare, but can involve poisoning and even death.


Great barracuda

Measuring up to 6ft, the great barracuda uses lightning speed and ambush tactics to catch its prey of fish.


The great barracuda’s fang-like teeth are very similar to those of a piranha, and there have been reported cases of barracudas leaping out of water and injuring boaters.


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