The 15 Most Dangerous Animals In Bali & How To Avoid Them

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Last updated on February 5, 2023 by Wandering our World

Bali is one of the most popular vacation spots in the world, filled with stunning beaches, unique wildlife, and lush foliage. There are beautiful mountains, great beaches and rice terraces you can explore when you’re planning a trip here, but the wildlife is spectacular as well.

But when planning your trip, it’s good to keep in mind that there are still many exotic animals in Bali that could be quite dangerous in certain situations. 

That’s no reason to not visit this beautiful country though, but it’s still important to know what animals to avoid, and how to avoid them. That’s what we’ll show you right here.

So keep reading to learn more about the most dangerous animals of Bali (with photos) and how you can make sure you can avoid them.

Young couple walking through rainforest

1. Red-Necked Keelback

A highly dangerous and extremely poisonous snake, the red-necked keelback, can be seen all over the island of Bali.

These snakes are most active during the day and are recognized by their red and yellow necks, olive green bodies, and black stripe that circle their neck. They are also able to flatten their heads and necks when put in positions where they feel threatened.

Red-necked keelback snakes are rear-fanged snakes, so they only grow to be about 60-80 cm long. As rear-fanged snakes, they must hold on after biting in order for the venom to be released.

They have strong jaws to keep the bite, but if they release, they may end up biting multiple times in a row. If bitten, and their venom enters the body, it can cause haemorrhaging and renal failure in the body. 

They are most often found near wetlands and water sources, sometimes slithering around on the forest floor. As when they go out to hunt, they are often searching for toads and fish.

And although they do not have a naturally aggressive disposition, they will defend themselves if they are presented with situations where they believe they are in danger.

The red-necked keelback is quite beautiful, but it’s best to stay away and admire from afar. 

Rhabdophis subminiatus, commonly called the red-necked keelback is a species of venomous snake in the subfamily Natricinae of the family Colubridae

2. Malayan Krait 

The Malayan krait is a carnivorous, venomous snake that averages around 108 centimeters in length.

They are easily recognizable by the dark brown, black, or blue stripes going down the body. These darker stripes are separated by white or yellow stripes.

The Malayan krait is a slow moving snake with a flatter tail to help them swim through water. Although these snakes prefer to stay close to the ground, they also spend some of their time swimming through the various bodies of water in Bali.

Malayan kraits are nocturnal, so it’s unlikely you’ll see them during the day, but you might find them out hunting for their food at night. They stay close to the ground, hunting smaller creatures like lizards, frogs, and other small snakes. 

The Malayan krait is not only highly venomous, but it is incredibly unpredictable. They don’t have a recognizable warning sign before striking a potential threat and their bites can be fatal to humans, and are well known as being one of the most dangerous animals you could come across in Bali.

Usually when bitten 5 mg of venom is injected into the body, however, only one milligram can prove to be lethal for some humans. The toxins in the venom slowly shut down the body’s nervous system. 

When walking, keep an eye open for these snakes, most people have gotten bitten when they accidentally step on one walking at night. It’s also smart to carry a flashlight with you. If you’re walking at night, you want to watch for potential threats along walking paths.

Highly venomous, Malayan krait or blue krait (Bungarus candidus) isolated on white background septiyana

3. Fire Coral 

Despite the name, fire coral isn’t actually a coral, but a hydrozoan. It’s more closely related to jellyfish, like the Portuguese man-o-war or anemones than coral.

Because of this, it can take a variety of different shapes. It often appears a yellowish-green or brown in color and likes to colonize on hard surfaces.

The way they form depends on the structure they’re forming on and ocean currents, because of this they may not always branch out. 

They are found in shallow reefs where there are high levels of sunlight. More often than not, people accidentally bump up against this hydrozoan, and it results in quite a painful burning sensation that can last more than a few hours.

Fire coral has a bunch of small hairs all over that sting anything that touches it. After coming into physical contact, a rash will develop on the burn site and can take a few days before it goes away.  

Though unpleasant for humans, fire coral actually plays an especially important role in marine ecosystems. It is incredibly strong and adaptable, which allows it to survive under stressors that would kill other types of coral, such as hurricanes and rising water temperatures.

Having fire coral in reef environments provides a home for fish, crustaceans, and other marine life, especially as other coral populations are declining. 

So, although unpleasant for us, it’s good to have them around. Luckily, their stings are not fatal, they just leave behind a painful mark that lasts a few days. 

Dichotomy fire coral (Millepora dichotoma) in the Red Sea, Egypt.

4. White Tip Reef Shark 

White Tip Reef Sharks are easily recognized by their striking white dorsal fin. They are nocturnal sharks that are found hunting for prey during the evenings, often searching for bottom dwelling creatures such as octopuses, crustaceans, and eels.

When hunting, they will chase their prey into an enclosed area, so it can’t escape and then they attack.

What stands out about these sharks is their ability to breathe without moving, they have been recorded laying at the bottom of caves, completely still. Usually, sharks get their oxygen from water and they have to constantly move in order to pump water through their gills producing enough oxygen for the body.

However, white tip reef sharks have evolved to possess a muscle that pumps water through their gills, helping them with this process. 

Their average length is 5.3 feet with a maximum weight of 40.3 lbs and they live to be about 25 years old. 

White tip reef sharks have been known to be aggressive toward humans and will attack when they feel threatened.

And though hunting this shark is frowned upon since this species is near threatened, if you happen to find it in a market, don’t try to eat it. The liver of white tip reef sharks is toxic for human consumption. 

Whitetip shark beside fish

5. Stray Dogs 

Bali is known to have a large number of stray dogs on the island, referred to as Bali dogs. In 2020, it was estimated there were 649,000 Bali dogs. 

When exploring Bali, it’s good to stay aware of these dogs. Some may appear aggressive and look rather unhealthy.

There are a portion of these stray dogs that possess rabies and if you’re bitten, rabies can enter the body and start attacking the central nervous system which can be fatal. 

However, oftentimes, these Bali dogs aren’t actually homeless. Instead, they are neighborhood dogs. They watch over areas and protect families of potential threats by alerting them when they witness an outsider. 

Bali dogs don’t belong to one household but are cared for by the entire neighborhood. They are very protective and if you get too close to one, you may notice they become hostile or turn aggressive. In their eyes, you are a potential threat to the neighborhood and they’re just trying to protect their family. 

Rabies wasn’t an issue until more recently in Bali, so they have taken action and are trying to prevent rabies from spreading to even more Bali dogs.

In recent years, Bali has started to vaccinate a lot of these dogs against rabies, and any dog that gets vaccinated is given a red collar to wear. If you notice a Bali dog with a red collar, it means they have been vaccinated against rabies, however, that doesn’t mean they won’t be aggressive.  

Fascinatingly, Bali dogs have been around for hundreds of years and are a part of life there. They help towns reduce food waste by eating food scraps, which decreases the number of rats and snakes coming to visit these towns.

Bali dogs are a large part of the culture in Bali and when you run into them stay aware of how they are acting toward you. If they seem aggressive, remain calm and slowly excuse yourself from the area. 

Cute dog looking up Studio

6. Sea Urchins 

Sea urchins are small, round creatures that are covered in long spines to steer off any potential predators.

They can be found in a wide range of colors, live up to 20 years old, and vary greatly in size. Depending on the species they measure anywhere from one inch to fourteen inches in diameter and weigh about a pound. 

In Bali, there are three main types of sea urchins, the Diadema setosum, Tripneustes gratilla, and Mespilia globulus.

Sea urchins are most often encountered when they get accidentally stepped on by an unsuspecting swimmer or diver. They produce incredibly painful stings that leave a puncture wound on the skin, which left untreated can get infected. These spikes can also break off after piercing the skin, getting stuck in the wound. 

After an encounter with a sea urchin, you might notice muscle aches, fatigue, and potentially paralysis. 

Sea urchins have a second, more active defense, called pedicellariae, which are small jaws that can release venom into their predators. 

These stings aren’t typically fatal, but they can be quite painful and inconvenient to deal with, especially on vacation.

It’s best to try to make sure you’re stepping on clear sand and if you do get stung cleanse the wound immediately and seek help if needed. 

walk on a sea urchin

7. King Cobra 

The king cobra is classified as a vulnerable species and can usually be spotted throughout west Bali. It is the largest venomous snake in the world so it’s unsurprising they are regarded as one of the most dangerous animals in Bali.

On average, it lives to be 20 years old and reaches 10-12 feet in length, but on rare occasions, it’s been known to reach 18 feet. Despite their large size, these snakes would rather escape danger than resort to aggression, and king cobras have only been reported attacking people when cornered. 

The king cobra likes to stay near streams in forests, seeking out areas that have consistent humidity and heat. They also like to spend around 25% of their time off the ground, in bushes or trees.

The king cobra is often recognized by the 11 scales on the crown of its head. They can also be found yellow, brown, green, or black in color with beige, or light yellow throats.

King cobras also possess excellent eyesight with the ability to see up to 330 feet away and they have a recognizable hiss that is very low in pitch, almost resembling a low dog growl. 

The king cobra has fangs that are around 0.5 inches and when biting their potential threat, the venom is delivered through glands in the fangs. Neurotoxins are released which start attacking the nervous system including the impulse to breathe which can be fatal to many animals, including humans and elephants. 

Seeing a king cobra in the wild can be quite shocking due to its size and distinct look. However, if you remain calm and don’t threaten them, they’ll likely leave you alone. 

King Cobra on brown sand.

8. Macaques

Macaques are small primates that are typically 41-70 centimeters in length and weigh 2.4-18kg. They are most often found with brown or black fur and have a round facial profile.

There are many different species of Macaques, some of them have evolved to have tails while others do not. In Indonesia, there are seven known species of Macaques. 

In Bali, the most commonly seen Macaque is the long-tailed Macaque. It has a pinkish-brown face and is covered in brown fur. Their tail is incredibly long, ranging from 1.3-2.15 feet in length.

Oftentimes, these Macaques are found living in groups, also called troops, the forest, or mangroves, staying near bodies of water. These Macaques are able to swim, and their diet consists mostly of fruit, but sometimes incorporates fish or crabs. 

Although, macaques are generally not aggressive, when threatened they can become aggressive and bite any potential threat. They have incredibly powerful jaws that result in painful bites and can spread disease to humans.

It’s best to avoid making direct eye contact with macaques, they view it to be threatening. You might notice these primates wandering around your stuff, they’re just curious and want to look through your belongings.

It’s unlikely they’ll seek out conflict, but it’s always best to air on the side of caution.  

Wild macaque monkey in natural environment Lagesse

9. Purple Jellyfish

The purple jellyfish is pelagic, meaning it is found swimming in clear, open waters. It’s a symmetrical creature with no organs, no centralized nervous system, and only one body opening.

At the base of the bell is a muscular ring that propels the jellyfish allowing it to swim. Jellyfish are quite delicate, and because of this, they have a relatively short lifespan, averaging between 2-6 months, with death usually resulting from rough waters. 

The purple jellyfish have been seen in large groups, referred to as shoals or blooms. Sometimes, these blooms reach up to 45 km in length and contain thousands of jellyfish.

Although, noticeable by divers when in large groups, on their own, these jellyfish are quite small, often only measuring 2 inches across. So, sometimes it can be hard to spot them before it’s too late and you’re already left dealing with a jellyfish sting. 

On the bottom of the bell, there are eight thin tentacles that produce a painful sting when you come in contact with them. The bell of this jellyfish is also covered in the cnidocytes, which sting their attackers.

The purple jellyfish uses their tentacles with little barbs on them to attack their prey and stun them.

These jellyfishes are venomous to humans and leave a whip-like scar on the body after sticking them. This area will be red and swelling that can last up to two weeks. Some people have also had allergic reactions to jellyfish stings that result in anaphylactic shock. 

Although, it is commonly portrayed in movies and TV shows, do not pee on sting wounds from jellyfish. The best thing you can do is remove the jellyfish, cleanse the wound with water and vinegar, and seek medical attention. 

Dangerous jellyfish Pelagia Noctiluca near surface

10. Mosquitos 

In Bali, mosquitos are very common and are known to carry dengue fever, which is an infection that is spread through female mosquito bites and leaves you in quite a bit of discomfort.

The most notable symptoms are severe headaches, muscle aches, and fever. Dengue fever has flu-like symptoms but can lead to a more severe dengue hemorrhagic fever. This is when blood vessels become damaged and can lead to easy bruising, hemorrhaging, and plasma leakage.

In some cases, it can be fatal or lead to amputation of the area that got bitten. 

When visiting Bali, it’s good to be aware of mosquitos as although small they are actually one of the most dangerous animals and insects you can encounter. If you’re in more densely populated areas, during or nearing the wet season, you will have a higher likelihood of contracting dengue fever.

When planning your trip to Bali, it’s best to consider bringing insect repellents and getting vaccinated against dengue fever before embarking on your trip. This will help offer some protection against the infection and hopefully reduce the risk of it becoming too severe. 

Mosquitos can carry other viruses, however in Bali, dengue is the most common. In tropical climates such as Bali, bites are hard to escape, but with some conscious acts and protective measures, it will hopefully allow for a smooth trip to Bali. 

mosquito biting someone's hand Sauko

11. Island Pit Viper

The island pit viper is one of the most commonly found dangerous snakes throughout Bali, and also one of the most deadly.

It’s not often spotted in densely populated areas, as it prefers more rural places and spends most of its time high up in trees. However, they will venture down to hunt at night.

The island pit viper also has some pretty distinguishing features, easily recognizable by its bright green color, red tail, and triangular head. 

Bites from this snake are not uncommon, and although these snakes are mostly above ground during the day, there is a chance they are hiding under a bush, or scavenging for potential prey.

If not paying attention, it can be easy to accidentally step on an island pit viper. If you get bit by one, there will be pain that can lead to swelling all over the body if severe enough.

The venom produced by this snake destroys the tissue and can result in internal bleeding. In Indonesia, these snakes don’t have any known antivenom, so if you get bit, it could lead to amputations or even death. 

When walking, it’s good to keep an eye out for creatures lurking below small shrubs and bushes, although you might not easily see them they can still feel threatened by your presence.

Wild white-lipped island viper photographed in a forest near Denpasar, Bali. Maguire

12. Javan Spitting Cobra

While the spitting cobra is much smaller in size than a king cobra, it is just as deadly.

The spitting cobra’s venom is equally as toxic as a king cobra – causing paralysis, cardiac arrest, and death. The spitting cobra has an added advantage in that it can spit its venom up to around 2 meters away, often blinding its victims.

Spitting cobras are often mistaken for non-harmful snakes, so it is best to be cautious of all snakes when exploring Bali.

The Javan spitting cobra Naja sputatrix or the southern Indonesian cobra isolated on white background septiyana

13. Black Widow Spider

These notorious spiders are identified by their hourglass-shaped marks on their abdomens. A black widow spider bite is reported to be 15 times stronger than a rattlesnake. Imagine that!

Another interesting fact is that only female black widow spiders bite. The bites of these spiders contain a neurotoxin called latrotoxin which can cause muscle aches, nausea, extreme pain, and breathing difficulty. The bite is so toxic it can be lethal, and elderly and small children are especially at risk if bitten.

Black widow spiders in Bali are usually found on the ground and in dark corners. Watch out for these dangerous ‘bandits who bite’ while exploring the beautiful landscapes of Bali.

Black widow spider dangling from a bush

14. Velvet Ant

Velvet ants are actually female wingless wasps that are covered in thick velvety hair. There are over 3000 species in the family of velvet ants and most of them are brightly colored to alert other animals to their presence.

Velvet ants are nicknamed ‘cow killers’, but their stings should only be fatal for small animals. However those stings are still excruciatingly painful for humans and could cause redness and swelling in the bitten area. Or even worse if you’re allergic – so always seek out medical attention if stung.

These wasps are typically non-aggressive though, and emit an audible squeak to warn predators away. 

Red Velvet Ant on Dry Dirt Path

15. Blue Ringed Octopus

This venomous octopus is generally smaller than others and can be spotted in tidepools and amongst coral reefs.

Measuring up to 10 inches in length. blue ring octopuses appear yellow, but when threatened their rings turn to a bright blue.

If this octopus feels threatened and attacks, their bites produce a toxin that blocks nerve signals. One might not notice the bite initially, but it can lead to muscle numbness, nausea, blindness, loss of senses and motor skills, and in the most severe cases can lead to death. 

Because of their bright color and small size, they are relatively easy to spot and might even look tempting to try and touch. However, if you see one of these, it’s best to create as much space as possible so they don’t feel threatened. 

The hovering blue ringed octopus

The Most Dangerous Animals In Bali: Our Final Thoughts

Bali has definitely earned its reputation for being one of the most beautiful and sought-after destinations to visit globally.

But when visiting Bali, it’s important to keep in mind the dangerous animals you could encounter.

However if you are cautious and don’t make animals feel threatened, it’s unlikely you’ll encounter anything too dangerous while you are there. Have a great holiday!


  • Wandering our World

    Hi and welcome to Wandering our World! This article was written by one of the Wandering our World team - a team of travel enthusiasts who live around the globe.