Environment

Curious visitors from the wider ocean.

Australian Sea Lion (Neophoca cinerea)

A critically endangered pinniped endemic to WA and SA. While their main colonies are on islands (e.g. Carnac and Shoalwater Islands south of Perth), lone sea lions occasionally venture along the metropolitan coast. Swimmers around Cottesloe may rarely encounter an inquisitive sea lion in the water or see one resting on a quiet beach. Their presence is infrequent but notable – they are a protected species and part of the region’s natural heritage. Sleek and agile, they have little ear flaps and big front flippers that let them “walk” upright on land and glide effortlessly through the sea. With their lighter, creamy coats and naturally curious nature, sea lions sometimes come close to swimmers, turning an ordinary dip into a truly unforgettable PodSquad moment.

Fur Seals (Arctocephalus forsteri)

New Zealand fur seals are also occasional visitors to our coast and are steadily making a comeback in Western Australia. Darker and shaggier than sea lions, they are bulkier in build but share the same external ear flaps and ability to move on land using their flippers. More often spotted lounging on rocks or swimming just beyond the break, fur seals bring a sense of wildness to the marine park. Their presence reminds us that Cottesloe is part of a much larger coastal habitat — one that deserves our care and respect.

👉 Key tip for PodSquad swimmers: If it looks sleek and light-coloured with a playful vibe, you’ve likely met a sea lion. If it looks dark, shaggy, and bulkier, it’s more likely a fur seal.

Masters of disguise with a curious mind.

The common reef octopus (Octopus spp.) is an intelligent mollusc frequently found in Cottesloe’s rocky areas. During summer, octopuses are especially active, foraging for crabs and crayfish at dawn and dusk. Divers might notice midden piles of shells outside a lair – a telltale sign of an octopus’s home. One species of small blue-ringed octopus also inhabits tide pools and shallow reefs; while reclusive, it is venomous, so observers give it space if spotted. Octopuses play a key role as both predator and prey (for example, they are known to sneak into lobster pots, much to fishermen’s surprise). Their presence year-round contributes to the biodiversity experienced by snorkelers, although they are most easily found in the warmer months.

Swift shape-shifters flashing colour in the shallows

Squid (Sepioteuthis australis) and the occasional cuttlefish (Cephalopods)can be spotted during their breeding season. The area serves as a breeding ground for squid, particularly the Southern Calamari squid. In spring and summer, squid lay clusters of egg capsules among seagrass and reef holes around Cottesloe. Snorkelers may spot these translucent white egg masses attached to weed. Adult squid are often seen hunting small fish and prawns in seagrass beds on calm evenings. Cuttlefish (e.g. the Australian Giant Cuttlefish and other Sepia species) are also encountered on local reefs – masters of camouflage, they flash patterns and colors. They tend to be more commonly seen in late winter and spring, when mating occurs; large males guarding mates can sometimes be approached by divers.

Graceful gliders and hidden hunters of the reef.

Smooth stingrays (Dasyatis brevicaudata) and eagle rays (Myliobatis australis) glide gracefully along the sandy seabed.  – Several ray species are regularly seen gliding over Cottesloe’s sand flats and reefs. The Smooth Stingray (the large black stingray) and Southern Eagle Ray are examples of rays that foragers can encounter in shallow water. They often cruise near reef edges searching for crustaceans. Smaller rays, such as stingarees (round rays), also inhabit the area. These elasmobranchs use the reef for shelter and breeding – for instance, striped stingarees breed in local waters alongside sharks and squid. While generally calm, stingrays should be observed from a respectful distance (they are usually seen year-round, with juveniles being common in warmer shallows).

Delicate drifters with a sting in their tail.

Seasonal blooms of jellyfish can occur offshore in summer (occasionally blue Physalia “bluebottles” wash in with the currents), reminding swimmers to be cautious on rare days when stingers are present

Bluebottle (Physalia utriculus) — Autumn–winter peaks on Perth beaches when onshore winds push them in. Floating blue oval “sail” at the surface; single long, beaded tentacle (often breaks off in surf). Do not use vinegar. Remove tentacles carefully; immerse in hot water (~42 °C) then cold packs as needed. Even dead ones on the sand can still sting.

Sea nettle (Chrysaora kynthia) — Summer appearances reported from Fremantle/Perth waters. Bluish-white, flattened dome-shaped bell (to ~12 cm) with frilly central mouth arms and 24 long tentacles; sting is extremely painful but not life-threatening. Do not use vinegar. Gently remove tentacles, rinse with seawater, then apply a bicarbonate-of-soda paste, followed by cold packs.

South Western Stinger (Carybdea xaymacana; a small box jelly) — Summer, especially in quiet bays around Perth/Rottnest. Tiny, almost transparent box-shaped bell (<3 cm) with one tentacle from each of four corners; attracted to lights at night. Sting mild to severe. Use vinegar liberally first, then remove tentacles and apply cold packs.

Colour, pattern, and rhythm — the reef’s living artwork.

Reef Fish (Wrasses, Parrotfish, etc.) – Cottesloe’s limestone reefs host an array of colourful reef fish. One of the most common is the Western King Wrasse (Coris auricularis), an endemic wrasse with vivid blue-green markings. This species is among the most frequently observed fish on Perth’s reefs (for example, it’s noted as one of the most common fish at nearby Rottnest Island. Males are larger with bright patterns, while juveniles act as “cleaner fish.” Other wrasses, like the brown-spotted wrasse, are also present.

Additionally, reef visitors might see Western Buffalo Bream(Kyphosus cornelii), large herbivorous fish (called “drummers”) that graze on seaweed – these are often seen in schools nibbling algae off rocks, especially in summer. Old Wife (Enoplosus armatus), a distinct black-and-white striped fish with tall dorsal fins, is another notable reef resident often found in pairs under ledges. These reef fish are generally present year-round, with activity and breeding usually peaking in spring and summer when water temperatures rise.

Flash mobs of silver and blue that bring the surf alive.

The waters off Cottesloe are regularly visited by schools of pelagic fish, especially in warmer seasons.

Australian Herring (Arripis georgianus, known locally as “herring” or “tommy rough”) form dense schools around reefs and jetty pylons, attracting predators.

Tailor (Pomatomus saltatrix) are common in summer and autumn – fast, blue-green predatory fish that hunt baitfish in the surf, often at dawn and dusk.

Silver Trevally(Pseudocaranx spp., locally called “skipjack”) and Tarwhine (Rhabdosargus sarba, a type of bream) frequent the area as well. These species forage around the reef and seagrass beds; snorkelers often encounter mixed schools of bream and trevally cruising the reef edge.

In autumn, the Western Australian salmon (Arripis truttaceus) migration (the “salmon run”) brings large schools of 4–8 kg salmon along the metropolitan coastline. Each autumn, millions of these Australian salmon move west and north, sometimes coming right into Cottesloe’s surf zone. Their seasonal run (peaking March–April) provides spectacular scenes of boiling baitfish and frenzied activity, occasionally even visible from shore, and can attract larger predators (and many fishing enthusiasts) as they pass through.

Quiet masters of camouflage on the sandy stage.

On the sandy seabed adjacent to reefs, divers and snorkelers can find bottom-dwelling fish like

Sand Whiting and King George Whiting (Sillaginodes punctatus). “KG” Whiting, prized for their taste, use the seagrass beds off Cottesloe as nursery areas – juvenile whiting are common in the shallows, especially in late spring and summer.

Flatfish, such as flounder or sole, may also be spotted partially buried in the sand. These species are generally cryptic but present year-round; many increase in number over summer when inshore waters teem with food.

Armoured reef guardians hiding in the cracks.

An iconic crustacean of WA’s reefs (locally known as “crayfish”). Cottesloe’s reef platforms provide shelter for juvenile rock lobsters, which hide in crevices by day. This species undertakes a well-known seasonal migration in late spring (the “whites” migration, when lobsters (Panulirus cygnus) molt and move offshore). Within the Cottesloe Fish Habitat Protection Area, all collection of lobsters is banned, allowing these crustaceans to thrive as part of the reef community. Divers on night dives often see their red eyes shining in torchlight. The Western Rock Lobster is not only ecologically significant as a predator and prey species, but also of high conservation value due to its fishery – Cottesloe’s protected status helps safeguard part of its population.

Camouflaged carpets of the reef, waiting in stillness.

Sometimes spotted by divers or early swimming risers. A small, docile bottom-dwelling shark common on temperate reefs. Cottesloe Reef is a known nursery area for Port Jackson sharks (Heterodontus portusjacksoni) and Wobbegongs (Orectolobus spp.). Each winter, adults migrate into coastal reefs to breed, and divers often find their corkscrew-shaped egg cases wedged in crevices. They are harmless to humans (aside from a dorsal fin spine) and feed on molluscs and crustaceans. Sightings peak in the cooler months when they congregate to lay eggs.

Tiny jewels that light up the reef.

Nudibranchs (Chromodoris spp., Phyllidia spp.): Tiny and colourful sea slugs often found by snorkellers on reef patches.  Colourful nudibranchs (sea slugs) are a favourite for macro photographers – these can be found year-round, with some species appearing more in late winter when plankton blooms occur. Cottesloe’s reef platform hosts many other spineless creatures.

Delicate feather stars (crinoids) cling to ledges at places like Mudurup Rocks, emerging at night to filter feed.

Bright red sea stars (including small six-armed starfish) and spiny sea urchins hide in crevices and graze on algae.

Sea cucumbers abound in the “cucumber gardens” on the reefs, recycling organic matter. 

Shell-clad grazers keeping the reef in balance.

Roe’s Abalone (Haliotis roei) populate the shallow intertidal reef ledges at Cottesloe. These small, green-shelled abalone graze on algae and were traditionally collected by snorkelers; however, in the marine park, all shellfish collection is prohibited. Abalone are most visible at low tides on reef flats. They spawn in warmer months, and their larvae play a crucial role in maintaining the local population. The presence of abundant abalone (a “shellfish” on the reef) indicates healthy algal growth and provides food for predators like rays and octopuses.

A rare ocean dragon draped in living leaves.

A rarer cousin of the weedy seadragon (Phycodurus eques), with elaborate leaf-like appendages. Leafy seadragons are more typically found further south, but on occasion, a lucky diver or swimmer in Cottesloe’s reefs might encounter one (they have been recorded in the area, though infrequently). They tend to prefer cooler months and very sheltered reef habitats. As a conservation-listed species (protected and Near Threatened), any sighting of a leafy seadragon is significant.

The reef’s leafy illusionist, hiding in plain sight.

An iconic fish species in Cottesloe’s waters. This leafy-camouflaged relative of seahorses lives among kelp and seagrass beds in shallow reefs. Cottesloe Reef is actually considered a hotspot for weedy seadragons (Phyllopteryx taeniolatus), and their presence signals a healthy reef ecosystem. They can be spotted year-round by keen snorkelers, though their superb camouflage makes them a special find. Notably, due to local conservation campaigns, the weedy seadragon was officially classed as a protected species in WA in 2011 – removing them or harming them is illegal. Males carry the eggs under their tail, and sightings of these bizarre yet beautiful fish are a highlight for divers.

Migrating giants passing Perth’s blue ocean super highway

Each year, humpbacks pass Perth on one of the world’s great migrations — heading north to warm Kimberley waters in winter, then south again in spring with calves at their side. Off Cottesloe, lucky swimmers and beachgoers may spot their breaches, tail-slaps, or even a mother resting with her calf close to shore. Protected and thriving after decades of recovery, these gentle giants are a breathtaking reminder of the ocean’s resilience. This species has made a strong recovery from whaling and is protected.

Heading North (Autumn–Winter) 🌏
From May to August, humpbacks migrate northwards from the cold, food-rich Antarctic waters. They travel along the WA coastline past Perth on their way to the warm breeding and calving grounds off the Kimberley.

Heading South (Spring–Early Summer) 🌊
From September to November, they migrate southwards back to Antarctica. This is when they’re most often seen off Perth’s beaches, as mother–calf pairs hug the coast on their return journey, resting in sheltered waters like those off Cottesloe before the long swim south.

👉 That’s why winter brings travelling whales, while spring brings breaching mothers and calves close to shore — the most spectacular time for PodSquad swimmers to spot them.

Rare winter visitors, bringing new life to sheltered shores

Endangered and precious, Southern Right Whales (Eubalaena australis) are only occasionally seen off Perth, but when they appear, they create unforgettable moments. Between June and October, mothers with calves sometimes venture close to Cottesloe’s calm waters while resting on their long migration. Their slow movements, distinctive callosities, and gentle presence remind us how vital it is to protect these rare giants and the fragile habitats they depend on.

Wetsuits make it bearable; bare skin makes it unforgettable.

As Roger Deakin says in his book Waterlog,”The problem about wearing a wetsuit is sensory deprivation; it is a species of whole-body condom. Of course, some people like rubber. They enjoy the feel of it; they may even find it aesthetically pleasing. But there is no getting away from the fact that a wetsuit is an anaesthetic to prevent experiencing the full force of your physical encounter with cold water, and in that sense, it is against nature and something of a killjoy. On the other hand, I tell myself each time I struggle into the rubber, not a drop of water ever actually reaches the skin of the otter. Its outer fur traps air in an insulating layer very like a wetsuit, and the inner fur is so fine and tight together that the water never penetrates it. So, if otters are allowed what amounts to a drysuit, I reckoned I could permit myself the occasional, judicious use of the wetsuit to bolster my chances of survival. It can make a long swim in cold water bearable, even comfortable, but it cannot approach the sensuality of swimming in your own skin.”

Brave the chill, embrace the thrill.

🥶 What to Expect

• Cold shock (first 1–2 min): fast breathing, gasping.
• Skin/muscles cool: strokes feel heavy, coordination drops.
• After-drop: core temp can dip after you exit.

✅ Steps to Acclimatise

1. Start small – 1–2 min dips, build up gradually.
2. Go often – 2–3 swims a week keeps adaptation.
3. Control breath – slow exhale, stay calm.
4. Splash first – face & chest before full immersion.
5. Gear up (if needed) – some heroes wear wetsuits 🦸🏼‍♀️.
   • Wetsuit = warmer, slower acclimatisation.
   • Double cap, neoprene booties/gloves = extra help.
6. Buddy system – never swim alone.
7. Get out warm – towel, layers, hot drink ready.

⚠️ Safety First

• Leave the water before you feel numb or shivery.
• Watch for fumbling hands, slurred speech = early hypothermia.
• Avoid hot showers straight after — warm up slowly.

📈 Adaptation Timeline

• Week 1–2: toughest, strong shock.
• Week 3–4: steadier breathing, longer swims.
• Month 2+: greater tolerance, quicker recovery.

🌟 Mindset

• Focus on the afterglow – mood boost, clarity, energy.
• Swim with mates – safer & more fun.