AUSTRALIAGiant Australian Cuttlefish AggregationIt has been called the ‘the premier marine attraction on the planet’ and attracts divers from far and wide eager to experience the only known dense aggregation of spawning cuttlefish in the world. It begins around the middle of May as the water temperatures drop and the first giant Australian cuttlefish (Sepia apama) gather just off from the rocky beach at Stony Point some 35km south-east of Whyalla in South Australia’s Spencer Gulf.

By early June, as the water drops below 17°C, the annual aggregation is in full swing and tens of thousands of these wonderful creatures will have gathered in an area of about 1km².

And they all have one thing in mind… sexual reproduction! So fixated are they on the task in hand, they almost completely ignore you and for the underwater photographer it provides an almost inexhaustible array of subject matter that just does not care that you are there!

It all happens in less than 8m of water and the cold water is really the only limiting factor as its all accessible from the shore.

Sepia apama is the world largest cuttlefish and when fully-grown can reach up to half a metre in total length and weigh in at up to 11kg. Solitary animals, they are found all around the coastline of southern Australia – from Central Queensland on the east coast, right around the bottom of the continent and up to Ningaloo Reef in Western Australia.

Truly fascinating creatures that have an amazing ability to instantaneously change their colour and skin texture. A skill they use to great effect as camouflage when they are hunting or being hunted, to communicate with other cuttlefish and as part of the amazing displays they use to great effect during the mating season.

Giant Australian cuttlefish are also remarkably intelligent and are said to have the largest brains of all marine invertebrates. The correct term for cuttlefish mating is polyandry – which means that each female cuttlefish will have multiple male partners to ensure better genetic variability of the species.

But with females outnumbered by as much 10 to 1, ‘spectacularly promiscuous’ would probably better describe the almost wanton behaviour!

Adding to that dynamic is the fact that the large, mature bull males are in their second year of life and will be dead by the end of the aggregation. Whether they know that is not clear, but they certainly act like they do…

The annual aggregation is truly a unique event that really should be on every diver’s Bucket List as there is nothing else quite like it!
Who to dive with
Scuba Courses
Did you know?To initiate sex, a male cuttlefish spreads his arms around his partner’s head.Essential informationLocation: Stony Point, Spencer Gulf, Australia
Depth: 8m
Diver level: Beginner

“ Giant Australian cuttlefish are also remarkably intelligent and are said to have the largest brains of all marine invertebrates ”