The 11 Most Dangerous Animals in Hawaii

dangerous animals in Hawaii

Hawaii is a collection of islands famous for its golden beaches, tropical climate, and unbeatable surf. The state comprises 137 volcanic islands set in the Pacific Ocean, about 2,000 miles from the US mainland. Due to their isolated position, many endemic forms of wildlife have evolved on the Hawaiian islands. While much of the state’s rich and varied wildlife is harmless, there are a fair few dangerous animals in Hawaii you’ll need to watch out for…

From the hoary bat to the Hawaiian monk seal, along with the state’s official bird, the Nene goose, Hawaii is famous for its booming biodiversity. It hosts many creatures that are found nowhere else in the world. The majority of these fascinating species pose no threat at all to humans. But that isn’t to say that visitors to Aloha are in for a totally risk-free time.

Nope, many of the most dangerous animals in Hawaii lurk off the state’s shores. We’re talking snapping sharks and stinging jellyfish, sea snakes and spiny urchins. You also get some on land, in the form of tropical snakes and spiders. So, what are these dangerous species, and how can you stop them ruining your once-in-a-lifetime adventure to the 50th state? Read on for a breakdown of the 11 most dangerous animals in Hawaii.

Box jellyfish (Cubozoa)

box jellyfish
Photo by Envato Elements

The first animal on our list of dangerous animals in Hawaii is up there with the deadliest of all. Cue the box Jellyfish. These potentially lethal marine animals live in the Pacific Ocean waters of the Southern Hemisphere. Also known as sea wasps and marine stingers, box jellyfish are recognizable for their cube-shaped bodies and tentacles.

Talking of the tentacles…Growing up to 10 feet in length, the long, dragging arms that go below the animal are covered with around 5,000 barbed stinging cells, called nematocytes. These help the creatures feed off a diet of shrimp and small fish, but the box jellyfish’s venom is also incredibly dangerous to humans. 

With toxins that attack the heart, nervous system and skin cells, box jellyfish venom can cause humans to go into shock and drown, or die of heart failure before managing to get medical help. Those that do survive experience excruciating pain for a number of weeks, and are usually left with some pretty gnarly scars.

Interestingly, unlike most jellyfish that drift on the tide, the box jellyfish is an intentional swimmer. This, and their translucent bodies, can make them more difficult to avoid in the water. Perhaps unsurprisingly, lifeguards in Hawaii are very vigilant when it comes to jellyfish. If any are seen close to the shore, it’s quite common that beaches will be completely closed. If you are unfortunate enough to be stung by one of these jellyfish, experts recommend covering the area with vinegar, carefully plucking out tentacles one by one, and applying a heat pad.

Sea urchins (Diadema setosum)

sea urchins
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Long-spined venomous sea urchins – locally known as wana – lurk in the depths of the Pacific surrounding Hawaii’s shores. While small and static, these spined creatures pack a nasty punch; a punch that many a scuba diver on an under-the-sea adventure in Hawaii knows all too well!

Sea urchins attach to coral, rocks, and other submerged surfaces in some of the state’s most popular surfing and diving spots. Unfortunately, this makes stepping on them a fairly common occurrence. In fact, ending up with a sea urchin spine in one’s foot is somewhat of a rite of passage among the state’s die-hard wave rider community. 

While by no means deadly, it’s certainly not a pleasant experience. The venom delivered from urchin’s spines can be very painful, and spines that break off and lodge in the body can be nigh on impossible to remove, though they will dissolve eventually. 

In order to avoid having a nasty encounter with a sea urchin, travelers should remember to wear sea shoes where possible. And even when wearing shoes, it’s important to remain vigilant and avoid treading on rocks and coral. If you do end up speared by an urchin’s spine, there are plenty of medical professionals in Hawaii well-equipped to offer help. Soaking the wound in warm water and vinegar helps to break down the venom. 

Cone snails (Conidae)

cone snail
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There are 34 species of cone snails in Hawaii. With pretty, intricately patterned shells, it can be tempting to collect cone snail shells for souvenirs. But be warned! Cone snails are actually some of the most dangerous animals in Hawaii. This is all down to their venom, which – in some sub-species – is known to be potent enough to kill an adult human in as little as five hours!

In fact, locals in Hawaii have nicknamed cone snails ‘dizzy shells.’ This is because their venom can induce anaphylactic shock in humans. As we mentioned before, there are a fair few different species of cone snail in Hawaii, and luckily, not all of them are dangerous. In fact, many have venom that is no more powerful than a bee’s sting.

But the toxins within the venom of three particular varieties – the textile, striated, and banded marble cone snails – are powerful enough to kill. Unless you’re an expert, it’s hard to tell one species of cone snail from another. So our advice would be to keep a wide berth of all snail-looking creatures and don’t go shell picking unless you’re with someone who truly knows their stuff!

Tiger shark (Galeocerdo cuvier)

tiger shark
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The tiger shark is one of the most dangerous sharks that live in Hawaii’s waters. Growing up to 13 feet in length, they have blunt snouts and tiger-like stripes on their torsos (hence the name). They are powerful near-apex predators, with an excellent sense of sight and smell. Tiger sharks are second only to great whites when it comes to confirmed attacks on humans, and are known to be particularly aggressive and territorial.

However, while films like Jaws have certainly given sharks a bad reputation, they don’t actually pose a great deal of threat to humans. This is particularly the case in Hawaii, where there are just 2-3 shark attacks per year, and very few are fatal.

Since records began in 1828, there have only been 11 shark fatalities recorded around these islands, mostly near the island of Maui. That’s a pretty low number if you consider the great deal of time that locals and tourists spend in Hawaiian waters. 

Nonetheless, it’s important to remember that when bathing in the Pacific, you’re entering the shark’s world. Following basic safety tips, using common sense, and listening to the lifeguard’s direction is essential in ensuring you don’t endanger yourself or the sharks.

Great white shark (Carcharodon carcharias)

great white shark
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While far less common than tiger sharks, great whites have also been seen off Hawaii’s shores. These legendary animals are the largest predatory fish on Earth – and definitely the most fearsome. They grow to an average of 15 feet in length, though some exceed 20 feet and weigh up to 5,000 pounds. With up to 300 razor-sharp teeth and a keen sense of smell, great whites eat a varied diet of other sharks, crustaceans, sea birds, sea lions, seals, and small toothed whales like orcas. 

Great whites are responsible for between a third and half of all annual shark attacks worldwide, but the majority of these are non-fatal. Great whites tend to ‘sample bite’ humans. In other words, they take only a little taste to see if they’re worth eating. After realizing they don’t like human flesh all that much, they tend to swim away.

Fatal attacks tend to happen when sharks mistake swimmers and surfers for seals or other prey. Thankfully, great whites remain very rare in Hawaii. Plus, they only tend to stray into the Pacific near the Aloha State in cooler season between January and April, which isn’t in line with the peak vacation time.

Moray eel (Muraenidae)

Moray eel
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Moray eels are one of the most dangerous animals in Hawaii. The state’s waters are crawling with them. Yep, there are over 80 species of moray eel in these parts, which can be found in holes and beneath rocks along the seabed and in offshore reefs. These slithering critters reach up to 13 feet in length and have two sets of very sharp teeth. They make for a pretty gruesome sight.

In 2018, a moray eel attacked a woman on Kuhio Beach in Waikiki, Hawaii. The wound was so painful that some thought she had been attacked by a shark. However, while moray eels can certainly exhibit aggressive behavior towards humans, these types of attacks are very rare. 

Eels tend to stick to themselves and are most active at night rather than during typical swimming hours. In order to best avoid them, simply don’t enter the ocean after dark (you shouldn’t be doing that at the best of times anyway!).

Yellow-bellied sea snake (Hydrophis platurus)

Yellow-bellied sea snake
Photo by Wikimedia Commons

Snakes are fairly rare on land in Hawaii, but its waters are home to a venomous variety of serpents. Chief among them is the yellow-bellied sea snake. As their name suggests, these are recognizable for their bright yellow underbellies. They have a brown upper body and can reach up to 35-inches in length. While they can stay underwater for up to 3 hours, they are sometimes seen in large groups of thousands, drifting on the surface and using the currents to wait for prey. 

Yellow-bellied sea snakes have a highly potent neurotoxic venom that is harmful to humans. However, they tend to be timid creatures that avoid contact, which is probably why there are no records of fatalities from yellow-bellied sea snakes in the Aloha State at all.

And they aren’t only unique to the 50th state of the USA. They actually exist in waters all around the Indo-Pacific region and beyond, from the archipelagos of Indonesia to the balmy shores of northern Australia to the Indian Ocean reaches of the Maldives and even the east coast of Africa.

Brown violin spider (Loxosceles reclusa)

Brown violin spider
Photo by Wikimedia Commons

Not all dangerous animals in Hawaii live in the sea. There are a number of spine-tingling creepy crawlies on land that you’ll want to keep a wide berth of. The brown violin spider is one of them… 

With long, spindly legs and violin-style markings on their back, it’s hard to miss brown violin spiders when you see one. While not typically aggressive, they have a reputation for biting in self-defense, especially during the autumn mating season. They pack a nasty bite, too which can cause vomiting, dizziness, and severe pain. 

Largely nocturnal creatures, brown violin spiders like to hang out in isolated spots – think under woodpiles and in sheds. It’s for this reason that these arachnids are known as recluse spiders in the US. Take extra care around dark, dank spaces if you want to avoid what could be an unfortunate encounter with the potential of ruining a vacation.

Brown tree snake (Boiga irregularis)

Brown tree snake
Photo by Envato Elements

Hawaii has no native snakes, and the state takes great measures to keep it this way. It’s illegal to own a snake, for example, and border officials rigorously check imports to ensure that not a single serpent slips through the proverbial net. Unfortunately, one species of snake has managed it: The brown tree snake.

Originating from Guam, brown tree snakes are an incredibly invasive species that pose a great risk to Hawaii’s birdlife. They have brown bodies, large heads, and protruding eyes. Brown tree snakes are mildly venomous and can exhibit very aggressive behavior towards humans. While their venom is not fatal to adult humans, it can be to children and people with compromised immune systems.

Brown tree snakes are still pretty rare in Hawaii. The authorities have been taking steps to try to cull the population before it grows too big and endangers the state’s fragile ecosystem. In 2018, for instance, the Hawaii Department of Agriculture imported four of the snakes in order to train sniffer dogs to hunt out the species. 

Stingray (Myliobatoidei)

Stingray swimming
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The Pacific Ocean that sloshes around Hawaii is home to a trio of ray species. The most famous is the manta ray, which is a large carpet feeder that looks truly elegant as it glides through the reefs. That’s the one that draws crowds of scuba divers to key feeding grounds in Maui and Kauai. Another is the stingray, which has a bit more of an unsavoury reputation…

Yep, stringrays are a cartilaginous fish that actually come from the same tree as sharks. However, they don’t attack with powerful bites and flesh-ripping teeth. They attack mainly with a venomous tail barb that can whip and stab victims at high speed. The good news is that they tend to avoid all human contact is possible.

But attacks do happen. Most famously, it was a wild stingray that killed the Aussie naturalist Steve Irwin back in 2006 during the filming of a documentary in the Great Barrier Reef. That’s far away from the sunny climbs of the Aloha State, but it goes to show just how dangerous these fish can be.

Coral reef snakes (Hydrophiinae)

Coral reef snake
Photo by Wikimedia Commons

Coral reef snakes are a pretty common sight in the tropical waters of the south Pacific Ocean and the Indian Ocean. They love to live in areas with balmy H2O temps and plenty of rock and coral coverage under the surface. That means everywhere from Indonesia to the Mexican Baja is fair game, with Hawaii smack dab in the middle there.

Thing is, aqua-based reef snakes remain very rare in Hawaii. Only a few anecdotal sightings of them have ever been reported on the islands. Most of the time, the only water snake seen in aloha is the aforementioned yellow-bellied sea snake. But we think they’re worth a mention nonetheless, especially since coral snakes are among the most venomous snakes of all!

Yep, certain types of coral snakes are known to possess ultra-powerful venom that can kill humans in just a matter of hours. That’s the bad. The good is that they’re almost all back-fanged snakes, which means they’ll likely need to bite you multiple times to inject enough of the stuff for it to be fatal. Divers are most at risk. Keep watch for snakes of about a meter in length, with alternating stripes of black and white running up the body.

The most dangerous animals in Hawaii – our conclusion

The most dangerous animals in Hawaii are mainly in the oceans that surround these islands. They lurk in the reefs – in the form of spiky urchins – and patrol the deeper seas and river mouths – in the form of tiger sharks and great whites. Swimmers will also need to pay especial attention to the arrival of jellyfish such as the box jelly, which can kill with just one sting. On land, the biggest worries are likely to be recluse spiders, but there are also some invasive brown tree snakes that are mildly venomous.

What is the most dangerous animal in Hawaii?

The most dangerous animal in Hawaii is the box jellyfish. These invertebrate predators have some of the strongest venom around. In humans, box jellyfish stings can lead to cardiovascular collapse and death as quickly as within 2 to 5 minutes. In fact, the 43 known species of box jellyfish cause more death and serious injuries than sharks, sea snakes, and stingrays combined. Luckily, however, the box jellyfish species found in Hawaii are not the most deadly of varieties. Still, it’s worth keeping an eye out for these cube-shaped creatures when swimming in Hawaiian waters. Their sting can be excruciatingly painful and leave skin permanently scarred.

Are there crocodiles in Hawaii?

There are no native crocodiles in Hawaii. The only place you’ll find these animals in Hawaii is in the zoo!

Are there poisonous spiders in Hawaii?

There are four native species of poisonous spider in Hawaii: the brown violin spider, the brown widow, the western black widow, and the southern black widow. The brown violin spider – aka the brown recluse spider – has long spindly legs and violin-style markings on its back. True to their name, these poisonous spiders like to keep away from human contact and hang out in isolated spots. However, they will bite if you come too close and are capable of administering a nasty venom that can cause severe pain.

Both western and southern black widow spiders have black bodies with red markings at the bottom side of their abdomen, but the southern species have an additional red dot on the abdomen. In general, male black widows are harmless – it’s the females you want to look out for. You can tell the sexes apart by size: the females tend to be much larger than the males, growing to half an inch long and up to an inch wide. Both varieties of black widows like to keep away from human contact in warm, dark, and isolated locations, such as garages and sheds. They will attack if someone disturbs their home, carrying a venomous bite that can cause cramping, nausea, hypertension, and pain.

The brown widow spider is less striking in appearance than its black and red cousins. It has a brown body with black markings. The brown widow makes its home in sheltered sites within vegetation and residential areas. While its bite is painful, it isn’t fatal. 

Fortunately, Hawaii’s native spider populations don’t tend to hang out in tourist areas. They prefer the residential areas and woodland to the beach, meaning that there’s little chance you’ll come across one unless you go poking in dark, damp, and isolated areas. All in all, poisonous spiders pose little threat to humans in Hawaii, so there’s no reason for arachnophobes to fear.

Are there deadly snakes in Hawaii?

Hawaii has no native species of snake – deadly or otherwise. This is partly owing to its isolated geographic position, and partly due to comprehensive efforts from local authorities to ensure that the state remains a snake-free zone. In fact, it’s a felony to possess or transport snakes in Hawaii, with violators risking a $200,000 fine and up to three years in prison. However, in spite of these best efforts, a couple of invasive species of snake have shown up in Hawaii in recent years. 

The mildly venomous brown tree snake, for example, has shown up on Hawaiin shores – but it poses more threat to the state’s birdlife than humans. Though rare, the yellow-bellied sea snake also populates Hawaiian waters. They carry a highly potent neurotoxic venom that is harmful to humans.

Finally, there’s the Brahminy blind snake – aka the Flowerpot Snake. Measuring at just 10 cm, this is the world’s smallest species of snake. Due to their size and their tendency to burrow into the soil, people frequently mistake these tiny, harmless critters for earthworms. Perhaps unsurprisingly, they pose no threat to humans – you could even say they’re kind of cute!


For more than 11 years, Joe has worked as a freelance travel writer. His writing and explorations have brought him to various locations, including the colonial towns of Mexico, the bustling chowks of Mumbai, and the majestic Southern Alps of New Zealand. When he's not crafting his next epic blog post on the top Greek islands or French ski resorts, he can often be found engaging in his top two hobbies of surfing and hiking.

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