The North Pacific Gyre, one of the largest ecosystem on Earth, is bordered to the south by the Intertropical Convergence Zone and extending north to roughly 50°N. At the southern boundary of the North Pacific Gyre, the North Equatorial Current flows west along the equator towards southeast Asia. The Kuroshio Current is the western boundary current of the North Pacific Gyre, flowing northeast along the coast of Japan. At roughly 50°N, the flow turns east and becomes the North Pacific Current. The North Pacific Current flows east, eventually bifurcating near the west coast of North America into the northward flowing Alaska Current and the southward flowing California Current. The Alaska Current is the eastern boundary current of the subpolar Alaska Gyre, while the California Current is the eastern boundary current that completes the North Pacific Gyre circulation. Within the North Pacific Gyre is the Great Pacific garbage patch, an area of increased plastic waste concentration.