Covering an area of 510,072,000 sq km, the world’s surface is approximately 71% water and 29% land. The huge proportion covered in water is divided into five major oceans: the Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern Ocean and Arctic Ocean. The land reaching out from these oceans forms seven basic continents: Asia, Africa, North America, South America, Antarctica, Europe and Australasia. With a population of approximately 6,800,000,000 people spread over 265 nations, the world is home to densely populated environments (the largest urban population being that of Tokyo, Japan, with 35,676,000 inhabitants) and vast, inhospitable locations where few, if anyone can exist (for example, Antarctica). Earth is the only planet in our solar system that is geologically active, with the landscape shaped by earthquakes and volcanoes that have created a diverse terrain ranging from the lowest point of -10,924 m (the Mariana Trench in the North Pacific Ocean) to the highest point of 8,850 m (Mount Everest in the Himalayas).