The physical geography of Canada is widely varied. Boreal forests prevail throughout the country, ice is prominent in northern Arctic regions and through the Rocky Mountains, and the relatively flat Canadian Prairies in the southwest facilitate productive agriculture. The Great Lakes feed the St. Lawrence River (in the southeast) where the lowlands host much of Canada's economic output. Canada has over 2,000,000 lakes—563 of which are greater than —containing much of the world's fresh water. There are also fresh-water glaciers in the Canadian Rockies, the Coast Mountains and the Arctic Cordillera. Canada is geologically active, having many earthquakes and potentially active volcanoes, notably Mount Meager massif, Mount Garibaldi, Mount Cayley massif, and the Mount Edziza volcanic complex.