Marion Bay Jetty

Marion Bay Jetty Dive Site Guide | Yorke Peninsula, SA, Australia

By ScubaDownUnder Team · 2026-04-21

# Marion Bay Jetty

A jetty at the gateway to Innes National Park on the southern Yorke Peninsula, with clear water, sea dragons, and good visibility compared to the sheltered northern gulf sites.

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## Quick stats

| Detail | Info | |---|---| | Location | Yorke Peninsula, SA | | Skill Level | Beginner | | Depth Range | 1–8 m | | Typical Visibility | 5–16 m | | Water Temperature | 13–20 degrees C | | Best Season | April–October | | Entry Type | Shore | | Hazards | Blue-ringed octopus present; Exposed to northwesterly winds; The southern Yorke Peninsula has limited medical services | | Facilities | Car park at the Marion Bay foreshore; Public toilets at the Marion Bay township; Camping and caravan park at Marion Bay, a good base for multi-day diving at the southern sites |

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Marion Bay sits at the entrance to the southern Yorke Peninsula just before the road enters Innes National Park, and its jetty occupies a transitional position between the sheltered upper gulf sites and the more exposed southern coast that the national park contains. The water is clearer here than the northern peninsula sites, a function of the deeper, more open conditions at this latitude, and the combination of sea dragons, cuttlefish, and the visibility that a calm day in this part of the gulf produces makes it a worthwhile stop on any southern Yorke Peninsula dive itinerary.

The bay opens to the west and northwest, and the jetty extends into water that deepens to around 7–8 metres at the outer end. The seagrass beds are extensive, stretching away from the jetty structure on the sandy floor in both directions, and it is in these beds, particularly in the zone directly adjacent to the pylons where weed meets structure, that weedy sea dragons are most reliably found. Leafy sea dragons are sighted with less regularity but are present at the site, and the lower depth and better visibility than the northern sites make spotting them more achievable on a productive day.

Giant cuttlefish aggregate here in the winter months with more predictability than at the smaller northern sites. The breeding behaviour of male cuttlefish, the intense colour changes, the competitive posturing, the deliberate slow approach to a female, is on display through the July to October window and is one of the most compelling wildlife encounters South Australian diving offers. Outside the breeding season, cuttlefish are present individually and in pairs throughout the year.

The northwesterly wind exposure is the practical variable at Marion Bay. These are the prevailing winds for the southern Yorke Peninsula coast, and they arrive with enough energy to chop the surface and reduce visibility in the shallow seagrass zone within hours of picking up. Planning a morning dive before the sea breeze establishes is the consistent strategy for this site and the others in the Innes Park vicinity.

## Site Access and Logistics

Marion Bay is approximately 265 kilometres from Adelaide via the Yorke Peninsula Highway and the Southern Yorke Peninsula road. The township sits just north of the Innes National Park boundary. Entry from the jetty steps. Open Water certification is appropriate. The Marion Bay caravan park provides a practical base for multi-day diving combining this site with the Ethel Wreck, Stenhouse Bay, and West Cape Reef. Tank fills in Yorketown (approximately 45km north).

## Sources

- [Ardrossan Barge](https://www.scubadownunder.com/blog/diving-ardrossan-barge-yorke-peninsula-south-australias-accessible-wreck-reef) - [Black Jetty](https://www.scubadownunder.com/blog/black-point-jetty-yorke-peninsula-dive-review) - [Cape Spencer](https://www.scubadownunder.com/blog/diving-cape-spencer-reef-yorke-peninsula-sa) - [Klein-Point Barge](https://www.scubadownunder.com/blog/klein-point-barge) - [Hardwicke Bay Jetty](https://www.scubadownunder.com/blog/hardwicke-bay-jetty)