Blue-ringed octopus - a guide for scuba divers and photographers

When it comes to muck and macro diving, the blue-ringed octopus is easily one of the most sought after subjects, and for good reason! This tiny octopus is one of the planet's strangest animals, combining pint-sized antics with some of the world’s most lethal venom. And, the sight of this psychedelic cephalopod is downright stunning. Its colourful display of neon blue rings is nothing short of spectacular – pictures simply don't do it justice! 

Whether you're an octopus lover that wants to learn more about these fascinating animals, or a budding macro fanatic hoping to find your first ‘blue-ring’ on a dive, you're in the right place. Read on to learn about this critter's camouflage, mesmerising blue-ringed warning dance, lethal venom, and more! We've also included a selection of very best dive sites to find them.

Cephalopods are some of the ocean's most captivating creatures, coming in all shapes and sizes. While the blue-ringed octopus is much smaller than most octopus species, ranging from 12 to 20 centimetres, its body is much the same as its larger cousins, with eight arms covered in small suction cups. And, it eats, mates, and generally lives in the same way. 

The blue-ring spends most of its life hidden away in the reef's nooks and crannies, emerging mostly to hunt. While this animal could potentially take down prey far larger than itself thanks to its powerful neurotoxin, it prefers a diet of tiny crabs and shrimp, with the occasional fish thrown in. Just like other full-sized octopus species, mating is a brief affair lacking in romance. The female blue-ring mates just once in her lifetime, starving to death slowly in her cave while she protects and aerates her clutch of eggs, ensuring the next generation's survival. 

When it isn't performing its beautiful blue warning dance, this animal isn't much to look at. Its mottled brown skin blends in with the surrounding rock and reef, making it particularly hard to spot. And, its use of dermal chromatophore cells to change colour and texture allow it to mimic the backdrop perfectly. 

So, what makes the blue-ringed octopus so special? Obviously, its signature markings are a major draw for divers and photographers. But, this animal's colourful blue display isn't it's only attractive attribute.

The camouflage and cryptic behaviour make them very hard to find and the excitement of spotting your very first one on a dive site is hard to beat. Blue-ringed octopus can also be surprisingly boisterous, putting on lengthy displays of colour changing, shapeshifting, and other fascinating behaviour. One minute, your subject could be posturing wildly, flaring out and curling its tentacles – and the next, it could be walking or jetting along the bottom, waving two arms overhead like a prizefighter. 

Keep your distance, and this show could go on for quite a while. But, disturb the presentation, and the octopus will likely dart away, using a jet of water to swiftly flee the scene. 

If the blue-ringed octopus is most famous for any one thing, it is probably its status as one of the ocean's most venomous animals. In fact, while each of these adorable little creatures is small enough to fit in the palm of your hand, just one milligram of their venom can kill a person – and there is no known antidote. This powerful neurotoxin, known as tetrodotoxin, is a powerful paralysing agent that the octopus thankfully only deploys as a self-defence measure.

Blue-ringed octopus spend most of their time well disguised in a boring brown, only flashing their signature iridescent blue rings as a warning or response to danger. While this neon colour show is obviously a big bonus for divers and underwater photographers, it's also a sign to take caution – and one that you should pay attention to.

The blue-ringed octopus is a master of disguise, using its texture and colour-changing skin cells to match any backdrop perfectly. It's also a cryptic animal, meaning that it spends much of its time sheltered in place under deep camouflage. So, in many cases, you'll swim right over one and not even know it.

Divers' movements will sometimes spook the octopus out of hiding, and then the show begins! In most cases, the octopus will start displaying erratic movements, curling and extending its tentacles, laying flat on the bottom and creeping, or using its vent to jet around. All the while, it will flash its unique namesake pattern of coloured rings – a warning to keep away!

If left undisturbed, some octopus will carry on this way for several minutes, allowing plenty of time to take pictures. But, if startled or harassed, the octopus will likely retreat quickly. 

Blue-ringed octopus can be found throughout the Coral Triangle and beyond, having been recorded from Australia, Papua New Guinea, Indonesia, Philippines, Malaysia and Japan. This small, cryptic critter prefers to hide out in rubble and reef with plenty of cracks and crevices to slip into, as well as small stones, seashells, and other items that can be used for camouflage. That's part of the reason they are so hard to find!

Blue-ringed octopus aren't just found on muck sites, so be sure to scan the coral, too, if you're diving in an area where they are commonly seen. And, consider your depth – this is an animal that's most commonly found in the shallows.

Feeling inspired to go on your very own macro quest? The blue-ringed octopus calls some of the planet's most exciting muck diving destinations home. Here are a few of our all-time favourites to add to your bucket list:

This diving area is known as Indonesia's "critter capital", and its reputation is well-founded. Lembeh's black volcanic sand and muck slopes are crawling with macro of all kinds. And, with some of Indonesia's very best spotters working in this region, you're almost guaranteed close encounters with all your favourite pint-sized wildlife. 

Another one of Southeast Asia's macro meccas, this destination has just as many critters as Lembeh and a similarly mucky bottom composition. But Anilao boasts surprisingly diverse diving options that are well worth your time, with a handful of thriving coral reefs close by, and legendary night dives – which are considered among the planet's very best by macro fanatics!

Known primarily as the gateway to Sipadan, Mabul and Kapalai are awesome places to look for all kinds of cool macro creatures – and take a break from Sipadan’s reefs and schooling fish. Mabul is also an excellent option for new muck divers, as the resorts generally offer a bit more hands-on guiding than places like Lembeh and Anilao.

Dauin and Dumaguete are diverse destinations boasting incredible muck and macro sites, bubbling geothermal vents, and excellent reef diving nearby. So, it’s no wonder that it’s quickly becoming one of the region’s hottest destinations. Visit during October or November for your best chances at spotting a blue-ringed octopus.

If reading this article has you feeling inspired, don't hesitate to get in touch. ZuBlu's team of travel experts will be happy to help you plan with all the latest travel tips and advice – right down to our favourite dive sites! We also offer support during your adventure, to make sure it's the trip of a lifetime.