The Burdekin is a river of extremes - bone-dry sand one season, a continent-draining torrent the next - but its real gift runs unseen. The delta sits on a vast aquifer of fresh water, and the man who taught the district to use it was an engineer named John Drysdale, who arrived in 1886. Drysdale adapted a clever device sometimes called the Abyssinian spear, a tube driven down into the ground to draw a steady flow without choking on sand or gravel. With reliable water came reliable cane, and the delta never looked back. Today the Lower Burdekin holds northern Australia's largest irrigation area - around 80,000 hectares under cane, producing well over a million tonnes of raw sugar in a good year, along with mangoes and vegetables. Drysdale is remembered on Queen Street, the main shopping strip, by a memorial clock raised in 1928. It is a fitting monument: in this town, time and water both keep the cane growing.

The green wealth of the Burdekin rests on a history that the town has had to learn to speak about honestly. Large-scale cane growing began here in 1879, and the first plantations did not run on free labour. They ran on South Sea Islanders - Pacific people from islands like those of present-day Vanuatu, drawn or seized into the trade known as blackbirding, a system that for many amounted to slavery in all but name. Between 1863 and the early 1900s, around 62,000 Islanders were brought to Queensland. The local record is stark. Of the 532 Islanders brought to the Airdmillan plantation near Ayr, 128 - nearly one in four - had died by 1885. These were not statistics to the families who lost them; they were sons and brothers and daughters, taken far from home to cut another country's cane, and too often buried in its soil. When the White Australia Policy forced mass deportations after 1901, many who had built lives here were torn away again.

But not everyone left, and their descendants are still here. The people of the Australian South Sea Islander community - many sharing both Pacific and Aboriginal ancestry - remain a distinct and proud cultural group across the Burdekin and the wider Queensland coast, keepers of a heritage their ancestors paid for dearly. Their story sits alongside the Italian families who came later to the cane, the Aboriginal Bindal and Juru peoples whose country this has always been, and the working-holiday backpackers who still arrive each year between March and December to swing through the harvest. The result is a town more layered than its quiet main street suggests. Creek names like Plantation Creek and a community that still gathers to say its own name out loud are reminders that the sweetness of the Burdekin has a memory, and that the memory is being kept alive by the people best placed to keep it.

Ayr stands on the northern bank of the Burdekin, and across the wide riverbed lies its twin, Home Hill, on the southern side of the delta. For decades the river divided them; then in 1957 the great Burdekin River bridge - the Silver Link, locally - was thrown across the gap, and at its opening it was the longest bridge in Australia. The two towns have leaned on each other ever since. Beyond the cane, the country has a cultural heart too: in the main street of Ayr sits one of Australia's finest small theatres, the Burdekin Theatre, a proper proscenium-arch house with a 473-seat raked auditorium, a fly tower and an orchestra pit, improbably grand for a town this size. And out past the river mouth, off nearby Alva Beach, lies one of the most famous dive sites on the planet: the wreck of the SS Yongala, Australia's largest and most intact historic shipwreck, lost with all aboard in a 1911 cyclone and now a teeming reef of its own, drawing more than ten thousand divers a year down into the warm dark of the Coral Sea.