Large circular ocean currents are known as ‘Gyres’ to oceanographers. Each of our oceans has them. They flow in a clockwise direction in the northern hemisphere and anticlockwise in the southern hemisphere. As they swirl around they collect any floating material and gradually push it to the centre. Thus huge patches of rubbish are formed in the middle of the ocean.

The North Pacific Subtropical Gyre lies between the equator and 50º N and covers an area of about ten million square miles. This appears to have the largest amount of rubbish and is also known as the Pacific Trash Vortex or the Eastern Garbage Patch. The garbage patch is said to be twice the size of the state of Texas. Most of the visible rubbish is, of course you guessed, plastic. Bottles, containers, nets, rings of six-packs, toys, plastic bags and so on. 

Scientists have measured six times more plastic than zooplankton in the North Pacific Gyre and more problems follow when the plastic is eaten. Plastic bags look like jellyfish to a hungry turtle, fish may eat small bits as do seabirds. Dutch researchers found 1,603 pieces of plastic in one bird and the UN estimates that plastic waste kills up to a million seabirds, 100,000 marine mammals and uncountable numbers of fish each year.

Nearer to home the Sargasso Sea is part of the North Atlantic Subtropical Gyre. This is the only “sea” without a shore and was until recently thought to be comparatively lifeless. It is however the home of the Sargassum seaweeds as well as having a major role in the life cycle of the eel and the Loggerhead Turtle. Due to the surrounding currents it also collects rubbish and has an ever increasing concentration of non-biodegradable plastic waste.