Point Cartwright & the Mooloolaba rocky reef

Point Cartwright is the low rocky headland at the mouth of the Mooloolah River, and one of the few places on the coast where you can read both faces of the sea country from a single spot: the hard and the soft, the reef and the meadow, a few hundred metres of rock apart.

Take a mask down to the shoals ringing the point, or to the rocky reef off Mooloolaba next door, and the hard face turns out to be a two-oceans reef. Why two oceans come to share one rock is worked out on other pages. At this address the point is simply that they do, and that the reef is only half of what Point Cartwright has to show. This is a worked headland, not a wild one, a stone shelf under a lighthouse and a suburb, and the reef holds on beneath the moorings and the outfalls all the same.

Off Mooloolaba, on the sand in about twenty-eight metres of water, lies a blunt demonstration of how readily the sea claims hard ground: the former HMAS Brisbane, a 133-metre guided-missile destroyer stripped, cleaned and scuttled in 2005. Bare steel is an empty lot, and the sea does not leave empty lots empty for long. Within months the hull fuzzed over with algae and hydroids, then crusted with sponges and corals, then filled with the fish that shelter among structure. The natural reef off the point does the same trick more slowly, on stone laid down long before us.

Then swim in behind the point, into the sheltered mouth of the river, and the ground under you changes. The bare rock, no place for a rooted plant, gives way to soft sand, and on the sand grows seagrass, the pale flowering pasture that shelters the inshore nursery and holds the sediment steady. The two faces are partners as much as neighbours. Many of the fish that hold on the reef as adults were spawned or sheltered as young in the calm of the meadow behind, so the animals themselves tie the rock country to the pasture, crossing the few hundred metres between as they grow.

The reef is the sea’s rock country and the meadow its pasture, set a short swim apart, each doing what the other cannot, and Point Cartwright is the hinge between them. It is the hard, seaward face of the land’s great gradient, the last of the range going under the waves, with the soft, sheltered face tucked into the river mouth just behind. Stand on the headland with the surf breaking on the rocks in front and the calm green shallows of the Mooloolah at your back, and you are where the country stops being something we can walk on. It does not end there. It becomes something we can only visit, and keeps going.