4 min read Underwater Perth

Shipwrecks of the Swan River

Shipwrecks of the Swan River
The Swan River from Point Roe, looking towards Blackwall Reach and Perth City.

The Swan River is full of shipwrecks, at last count more than 30. They are a favourite when the weather turns bad for ocean shore diving. This week I've chosen the Mayfield and City of Perth wrecks to snorkel, and Blackwall Reach to dive.

The Mayfield and City of Perth Shipwrecks

Rocky Bay, Fremantle. Depth 1-4m. Snorkel or Dive.
Slack tide (when currents are lowest).

Rocky Bay is a spectacular example of a maritime landscape. The limestone cliffs were host to some of Fremantle's early industries, many remnants of which still survive.

Rocky Bay, looking over the old Burford's Soap Factory. The shipwrecks are beneath the cliffs.

The Mayfield and City of Perth shipwrecks lay next to each other, below the cliffs of Rocky Bay. Mayfield was a barge used to carry armour plating over to Rottnest Island for the guns at Oliver Hill, part of Perth's WWII defences. It wrecked in 1945. City of Perth was a paddle steamer, carrying cargo on the river itself. It is older than Mayfield, wrecked in 1890.

City of Perth and Mayfield shipwrecks from above. City of Perth is closest to the shore, with the Mayfield just visible further out.

On a clear day, the Mayfield can be seen from the surface. It can be snorkelled or dived from the shore, but is best done by boat. If you swim along the cliffs you will find the City of Perth wreck in just a metre of water. Mayfield is just 15m out from there, in 4m of water.

Divers on the Mayfield wreck.

When diving the Mayfield site look for the two engines on either end, the stern one for propulsion, and the bow one for a jib crane.

3D Model of Mayfield, December 2021.

Blackwall Reach

Bicton. Depth 5-18m. Dive.
All weather.

Blackwall Reach is best known for the Blackwall Reach Barge. Like many wrecks in the river, it was sunk on purpose - abandoned by the The Goldfields Metal Mining Company in 1967. As always, Dave Jackson has great advice on finding this wreck (under mooring 716), and the others nearby.

Diving Blackwall Reach after heavy rains (July 2021). This is the in the middle of the day.

I enjoy diving the shipwrecks at Blackwall Reach, but there are some interesting sites closer into the cliffs. If you follow the 8m depth contour along to where people cliff-jump, you will find all sorts of dumped items - including cars.

Conditions can vary substanitally throughout the year. Sometimes, after heavy winter rains, the tannins washed downstream stain the water a very dark brown. This murky freshwater runs over the saltwater beneath, forming a cap that blocks out all the light. The water can be quite clear below this halocline (transition from fresh to salt), but you will need a torch.

One of the Blackwall Reach cars

This stretch of the river is known for being the deepest - with a channel going past 18m. The very deepest point is just upstream, at 22m metres - the site of the Mosman Bay Barge. This is clearly where people go to get rid of trash... or things they want to hide. It is no longer possible to dump cars here, after a barrier was installed, so this is a record of insurance-frauds-past.

Various dumped items at Blackwall Reach.

Every Thursday this summer I will be writing about one dive and one snorkel site around Perth.

Next week's theme is: 'Down South'. Today's blog was meant to be 'day at the beach', but that will come a little bit later. The visibility is terrible in Perth's coastal waters this week, apart from Rottnest (see my other site: https://vis.report).

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