After examining the footwear drifting onto Queensland's north coast, the Townsville-based researcher offered an explanation. "My proposal is that right-footed thongs will be separated from left-footed thongs as they drift down the ocean currents," Mr Carlos said. "So in theory, left-footed thongs should be pushed to the outside of the South Pacific and right-footed thongs should be pushed to the centre of the South Pacific."



The separated thong theory is based on ocean currents and the fact that right- and left-foot thongs are asymmetric. According to the hypothesis, Australia's east coast and countries on South America's west coast, such as Peru, would have a left-foot bias.

"But the island nations right in the centre of the Pacific like French Polynesia, maybe Samoa, they would have a heap of right foot thongs," Mr Carlos said. "The countries in between would have a bit of a mix." But Mr Carlos said his hypothesis could only be proved by a research expedition to key areas of the South Pacific.

Thongs dominate the footwear that washes up on Australia's north coast, thanks largely to their popularity in the tropics. But in the northern hemisphere, all sorts of things turn up on beaches and islands due to crates falling overboard during storms, Mr Carlos said.

Items believed to be floating in the world's oceans include 29,000 rubber ducks and five million lego pieces, he said. "In 1990, 80,000 Nike (runners) went over the side in the North Pacific, and they've been turning up on the beaches from Canada to Mexico." AAP