Phillip Island: Kelp Beds Below the Penguin Parade

Every evening of the year, a few thousand people sit on grandstands at the southwestern corner of Phillip Island and watch the world's smallest penguins come home. It is one of Australia's great wildlife spectacles, and it has made the island famous. What the grandstand crowd is looking at, though they may not know it, is the visible tip of a kelp coast. The penguins fish the water column above the reefs; the reefs hold the fish; the kelp holds the reef. Pull on a hood and drop beneath the Bass Strait swell off the Summerland Peninsula and you find the rest of the show: golden kelp forest, sponge gardens, fur seals barrel-rolling through the surge, and the cold green machinery that makes a penguin parade possible.

Reading this atlas entry

Phillip Island lies about 140 kilometres southeast of Melbourne, where Western Port opens into Bass Strait — the shallow, storm-worked seaway between mainland Victoria and Tasmania. The island is small (about 100 square kilometres), connected to the mainland by a bridge at San Remo, and layered with three coasts of different character: a north-facing bay shore on Western Port; a rugged southern ocean coast of basalt cliffs, surf beaches and kelp; and the offshore island of the Nobbies and Seal Rocks at its western tip. It sits squarely within the Great Southern Reef, the interconnected temperate kelp system spanning Australia's southern coastline.

Three coasts, three moods

The north coast faces Western Port, a broad tidal embayment famous for its seagrass meadows, mangroves and migratory shorebirds. This is the island's calm workshop — shallow warm water, seagrass rather than kelp, and the nursery habitat that quietly feeds systems further offshore.

The south coast is the kelp coast. From Cape Woolamai's pink granite around to the basalt of the Nobbies, the shore alternates between high-energy surf beaches — the island is a major Victorian surf destination — and rocky platforms and reefs where the swell concentrates. Below the wave line the rocky reef runs out into depths of 10–25 metres before giving way to sand, and on that reef the forest grows.

The west end is the wildlife citadel: Seal Rocks, two kilometres offshore of the Nobbies, hosts one of Australia's largest breeding colonies of Australian fur seals, and the Summerland Peninsula is the stronghold of the island's little penguins. A marine national park at the Nobbies protects the surrounding waters.

The kelp, and what grows with it

The dominant canopy-former is golden kelp (Ecklonia radiata), the backbone of temperate Australian reefs, clothing the offshore bomboras and low-relief basalt reefs in a dense golden-brown canopy. On the most exposed rock, bulls' kelp (Durvillaea potatorum) — the leathery southern bull kelp that Foveaux Strait shares with this coast — takes the full brunt of the swell, its honeycombed fronds engineered for exactly this punishment. Beneath the canopy, the understory is distinctively southern: branching brown algae, encrusting pink coralline algae, sponge gardens, ascidian fields and the jewel anemones that turn shaded walls orange and pink.

The fish life reads like a Great Southern Reef field guide: Port Jackson sharks cruising over the sand in the cooler months, draughtboard sharks resting in the ledges, schools of bastard trumpeter and striped trumpeter along the reef edges, and the wrasse guild doing its endless gardening among the fronds. With patience, the kelp margins reveal the coast's most celebrated camouflage artists, the weedy seadragons. Dolphins work the strait year-round; humpback and southern right whales pass along the coast on migration; and through winter the penguins' world extends far into Bass Strait, where they forage over the shelf.

A coast with a full accounting of pressures

Phillip Island's reefs are healthier than many on this coast, but they live inside the Bass Strait — one of Australia's most energy-rich, most variable seas — and they carry the region's shared ledger of risks:

• Marine heatwaves. The southeast Australian seas are among the fastest-warming temperate waters in the world, and Bass Strait has suffered severe marine heatwaves. Kelp species near their warm limits — the region's giant kelp remnants can no longer be taken for granted — face compounding extremes.
• Urchin expansion. The long-spined sea urchin (Centrostephanus rodgersii) has been marching south from New South Wales with the strengthening East Australian Current, and Victorians watch its Bass Strait range anxiously; the pattern of what follows is described in our explainer on urchin barrens.
• Nutrient and runoff inputs. Western Port carries catchment runoff from a growing coastal region; the bay's seagrass history includes one of Australia's largest losses — a reminder that coastal eutrophication hits kelp and seagrass meadows alike.
• A busy coast. Shipping, fishing and recreational pressure concentrate at the island's water; the summer population surge strains every system at once.

The penguin lesson

What makes Phillip Island worth an atlas entry of its own is not just its natural history but its management history. In the 1970s the penguin colony was in trouble — roads, housing and disturbance pressed right to the burrows, and the population was falling. The response was one of Australia's more quietly radical conservation projects: the government progressively bought back an entire housing estate, demolishing homes at the Summerland Peninsula and returning the headland to penguin habitat, while a research program turned the island into one of the best-studied little penguin colonies on Earth. It worked. The colony remains internationally significant, and the buyback stands as a rare case of a developed coast simply stepping back.

For those of us in restoration, this is the story's real value: recovery is a choice, and it is achievable. The same logic underlies Tidewright's solutions for coastal governments — that the economics of tourism, fisheries and coastal protection can align with the biology rather than fight it.

Visiting, briefly and honestly

The penguin parade is run by Phillip Island Nature Parks and books out in peak season; buy in advance and bring a jacket whatever the forecast says — Bass Strait weather is its own country. Seal-watching cruises run to Seal Rocks from Cowes. For the kelp coast itself, the clifftop walks at Cape Woolamai and the Nobbies boardwalk give you the stage; diving charters from San Remo and Rhyll serve the local reefs for those who want the understory, and our beginner's guide to kelp diving is the checklist for anyone making the leap from grandstand to wetsuit.

Key takeaways

• Phillip Island, 140 km southeast of Melbourne, holds three distinct coasts: sheltered Western Port seagrass in the north, a kelp-bearing ocean south coast, and the seal and penguin citadel at its western end.
• Golden kelp and southern bull kelp form the forests; sponge gardens and weedy seadragons complete the understory.
• The island's wildlife economy — penguins, fur seals, whales — is downstream of the reef and its kelp.
• Heatwaves, urchin range expansion and coastal runoff are the ledger of pressures, as they are across the Great Southern Reef.
• The Summerland Peninsula buyback makes Phillip Island a global reference case for coastal restoration by retreat.

FAQ

When is the best time to see the penguins?

The little penguins come ashore at dusk every day of the year, with larger numbers during the breeding and moulting seasons. Arrive at least an hour before sunset and dress for Bass Strait cold regardless of season.

Can you dive Phillip Island's kelp reefs?

Yes — charter operators run from San Remo and Rhyll to the south coast bomboras and offshore reefs. The water is cold (roughly 12–19 °C) and conditions are weather dependent; go with local knowledge and full temperate-water gear.

What kelp grows there, at what depth?

Golden kelp (Ecklonia radiata) dominates the offshore reefs typically below 5–10 metres, while bull kelp occupies the most wave-battered shallow ledges. Some historical records of giant kelp and other deeper laminarians mark the island as a southern mixing zone.

What happened to the Summerland housing estate?

From the 1980s onward, the Victorian government progressively purchased and demolished the holiday housing estate on the penguin colony's headland — around 900 lots — restoring the peninsula to habitat. The buyback is widely credited with helping stabilise the penguin colony.

Is Phillip Island part of the Great Southern Reef?

Yes. Its reefs sit within the temperate kelp system spanning Australia's southern coastline — the Great Southern Reef — with fauna and ecology matching that temperate family.