Plastic is photodegradable, or broken down by solar energy, which means the plastic in the ocean is continuously breaking down into smaller and smaller pieces. Fish mistake these plastic shreds for plankton, and they in turn are eaten by other fish, which are then caught for human consumption.

The Plastic Vortex was discovered by oceanographer Charles Moore in 1997, but public apathy and lack of funding mean that most people are not even aware of its existence. But next month, a group of United Nations-backed volunteers will stage the largest and costliest clean-up of the Plastic Vortex.

Setting out from San Francisco, Project Kaisei will sail for five days to the island in July, where members will extract waste and research ways to recycle the plastic into biodiesel fuel, a proven but expensive source of energy. The team of researchers also aims to determine the impact of plastics in the food chain.

'The biggest problem is that the Plastic Vortex is ... it's in international waters, so no one wants to take responsibility,' said Andrew Boyce, a Year 12 student at the Chinese International School who has been volunteering his time to promote the mission through online channels.

Project Kaisei - the name of the team's 50-metre boat and the Japanese word for 'ocean planet' - will make two journeys, and needs US$2million in donations to cover its costs. National Geographic filmmakers will be on board to document the journey, while crew members will communicate with the world through Twitter and blogging.

Project founder and conservationist Doug Woodring, who lives in Hong Kong, said the group was still unsure of the ship's capacity, so it was not actively seeking student volunteers, but he would keep interested parties in mind. He said there were many other ways to help out without setting foot on board.

First, reduce your own consumption of plastic. This will mean less plastic in our landfills and beaches, and less chance of it going into the ocean. According to Project Kaisei, about 80 per cent of the plastic waste in the ocean comes from illegal land-based dumping.

Mr Woodring also advised students to raise awareness at their schools. 'We can help conduct programmes if schools are interested,' he said.

People can also participate in Ocean Cleanup Day on June 6 and 7. 'Get out on the water for three hours and see how much waste you can pick up from the sea or shores,' Mr Woodring said. On June 8, Project Kaisei will sort through the trash to show students what was found.