Arctic Ocean gas reserves, and the Chukchi shelf forms the border between Russian and the United States as stated in the USSR–USA Maritime Boundary Agreement. The whole area is subject to international territorial claims. An underwater ridge, the Lomonosov Ridge, divides the deep sea North Polar Basin into two oceanic basins: the Eurasian Basin, which is between deep, and the Amerasian Basin (sometimes called the North American, or Hyperborean Basin), which is about deep. The bathymetry of the ocean bottom is marked by fault block ridges, abyssal plains, ocean deeps, and basins. The average depth of the Arctic Ocean is . The
Sistan Basin Mount Khajeh, rises beside the lakes and marshes of the basin. The lowest part of the Sistan Basin contains a series of shallow lakes, known as "hamuns". It appears that in the past there was a single Hamun Lake, but there are now three separate lakes. From north to south the lakes are: The Hamun-e Puzak lies mostly in Afghanistan. It receives water from the Shelah Charkh channel of the Helmand River, and also from the Khash River and other small rivers. The Hamun-e Sabari is split between Iran and Afghanistan. It receives water from the Parian branch of Helmand