The United States challenges Canada for the title of the largest country in North America, but the latter just edges it. Being the second largest country in the World, Canada is an enormous land, stretching from the Atlantic Ocean in the east to the Pacific Ocean in the west. It's northern border runs along the Arctic Ocean, and it's borders with the United States - to the south and along Alaska - are the longest common border shared by any two countries on the planet. Canada's population density is one of the lowest in the World, with just 3.5 inhabitants per square km, and it holds most of the World's fresh water in the largest collection of lakes on Earth. This notably cold land is also active in a geological sense, with regular earthquakes and many potentially active volcanoes.