In 1973 three experimental tyre reefs were laid on the sand close inshore along the eastern side of Port Phillip as an early attempt at artificial fishing habitat. Two have since collapsed or been buried; the one off Chelsea survives and is the only piece of structure on an otherwise empty stretch of sand between Mordialloc and Frankston. It is built of about a thousand tyres bound into bundles and weighted with quarry rock, concrete cubes and steel frames, forming a low mound in 10 m of water roughly 2 km off the beach.

After fifty years the tyres are heavily overgrown with red algae, sponges, ascidians and hydroids and the reef functions much as a natural boulder pile would. Fish life is good for its size: snapper (both juveniles and the occasional decent fish in spring), boarfish, red mullet, leatherjackets, ling, beardies and bearded rock cod in the crevices, long-finned pike and baitfish above, and a range of smaller wrasse and gobies, with octopus in the tyre bundles and flathead and rays on the surrounding sand. It is a compact site that can be covered in twenty minutes, so most divers do a slow lap or two concentrating on the holes and undersides.

It is heavily fished, which brings snagged line and hooks and a steady procession of boats overhead, so a surface marker and a careful ascent up the anchor line matter. Historically it is interesting as one of the earliest artificial reefs in Victoria and a reference point for the modern concrete-module reefs at Aspendale and Seaford, which are natural companions for a two-dive small-boat morning out of Patterson River.

Launch at the Patterson River public ramp at Carrum (large ramp, plenty of trailer parking) or at Mordialloc Creek and run 2-4 km to the mark, about 10 minutes. The reef is unmarked on the surface, so use the GPS position and a sounder to find the mound, anchor on sand beside it and descend the anchor line. It is well used by anglers, so approach with care and fly an A-flag.

Exposed open-bay site: light northerly to easterly winds only; fresh southerlies through westerlies make it choppy and stir the fine sand. Best on the flood tide in autumn and winter when the water is clearest; poor after rain because of the Patterson River outflow just to the south. No swell.

Summer afternoon sea breezes build quickly on this shore.

Descend the anchor line to the sand at 10 m, circle the mound of tyres and rock keeping it on one shoulder, look into the tyre bundles and under the steel frames for fish and octopus, return to the line at half gas and ascend with a short stop at 5 m.

No regular operator – private boats and dive club RIBs only.