The Bluff (Rosetta Head)

The Bluff (Rosetta Head) Dive Guide, Victor Harbor

By ScubaDownUnder Team · 2025-09-20

After the algal bloom. The Bluff was one of the best places near Adelaide to look for a leafy seadragon, but the Encounter Bay coast was among the areas worst hit by the 2025 harmful algal bloom. In September 2025 the IUCN's seahorse, pipefish and seadragon specialist group listed it, with western Gulf St Vincent, southern Yorke Peninsula and northern Kangaroo Island, as a heavily impacted region where thousands of young seadragons due in late 2025 and early 2026 would be lost. A dive report passed on by the Scuba Divers Federation of South Australia (SDFSA) in November 2025 found shrimps, magpie perch, zebrafish, a few cowfish and a 1.5 metre fiddler ray in the seagrass, with the kelp and seagrass looking healthy, but the sponges, sea squirts and soft corals under the ledges wiped clean.

We have not found a published report of a leafy seadragon at The Bluff since the bloom. Diving Adelaide's page, last updated in March 2026, still describes a very healthy population, so ask the shop about recent sightings rather than relying on it, and if you do find a seadragon, add your photos to SeadragonSearch, which tracks individual animals. In October 2026 SARDI's satellite data also showed chlorophyll above normal for the time of year in the nearshore water from the Murray Mouth to Victor Harbor, with marine heatwave conditions in both gulfs, so check the state's algal bloom updates before you go and stay out of discoloured or foamy water.

The Headland

Rosetta Head, almost always called The Bluff, is the granite dome at the western end of Encounter Bay, 97 metres high, about 3.9 kilometres south-west of the centre of Victor Harbor and 77 kilometres south of Adelaide. The Ramindjeri people know it as Longkewar or Kongkengguwar. Its rounded shape was ground out by a glacier in the Permian, long before the sea rose around it about 7,500 years ago. A whaling station worked from the headland from 1837 to the early 1860s, and its summit was the whalers' lookout.

The Dive

The SDFSA's site notes describe big granite boulders stacked on top of one another, with holes, ledges and swim-throughs, and give depths from 4 to 40 metres; state charts quoted by Wikipedia put the water off the base of the headland at up to 12.8 metres within 100 metres of shore. Before the bloom the holes held a wide variety of sponges and soft corals, and the SDFSA, The Dive Shack and the state's environment department listed leafy and weedy seadragons, seals and sea lions, seahorses, crayfish, nudibranchs, dolphins and plenty of fish.

Diving Adelaide's dive plan keeps the rocky reef and weed on your right shoulder on the way out and on your left on the way back, and turns around once you feel the current pick up. It says a small colony of weedy seadragons lived where the current starts, though you had to be lucky to see them, and that there are usually lots of particles in the water even on better days.

Conditions

The Bluff is exposed. Diving Adelaide says it is open to all but northerly winds and best dived after a few days of northerlies, and the state's environment department notes that it can be dived year-round if you plan ahead and pick a good day. The Dive Shack warns of tricky currents even on calm days and large waves that can appear out of nowhere.

The Bluff lies inside Encounter Marine Park. Diving is allowed in every South Australian marine park zone except restricted access zones, and vessels must keep 300 metres from any marine mammal in the Encounter Bay whale calving and nursery area.

Site Access and Logistics

Diving Adelaide's recommended entry is the safest: park at the little beach in the bend, walk down the stairs, enter from the beach and swim out to the little fishing jetty. Fit divers can also park at the jetty and climb down its ladder, but Diving Adelaide advises against climbing in over the slippery rocks beside it. The shop runs guided leafy seadragon dives here when there are northerly winds, which it says are not common, about an hour and a half's drive from Adelaide, and rents gear for buddy dives. For other Fleurieu seadragon sites, see Second Valley and our Rapid Bay Jetty guide, where the old jetty is now closed to divers.

Sources

- IUCN SSC Seahorse, Pipefish and Seadragon Specialist Group: Thousands of seadragons dead in South Australia's worst recorded harmful algal bloom - Scuba Divers Federation of SA: newsletter of November 2025, and Where to dive, sdfsa.net - PIRSA SARDI: Algal bloom situation update, October 2026 (pir.sa.gov.au) - Government of South Australia: Algal Bloom Update (algalbloom.sa.gov.au) - Diving Adelaide: Dive The Bluff in Victor Harbor - Diving Adelaide: Guided Leafy Sea Dragon Dives - The Dive Shack: Local dive sites, Fleurieu Peninsula - SA Department for Environment and Water, Good Living: Discover South Australia's must-visit dive spots - Wikipedia: Rosetta Head - Marine Parks SA: Encounter Marine Park - Marine Parks SA: Zones - SeadragonSearch

Header photo: Victor Harbor around 1925, with The Bluff on the skyline and part of Granite Island and its causeway at far left, by the South Australian State Government Photographer, CC0, via Wikimedia Commons.