the murghab river and the tejen river flow from afghanistan but peter out in the karakum desert. the atrek river is a shorter river flowing from iran, but only reaching the caspian sea in time of flood. the amudarya river flows northwestwards near the border with uzbekistan before emptying into the remnants of the aral sea. garabogazköl gulf is a large shallow lagoon that is sometimes connected to the caspian sea and has a much higher salinity, surpassing the far-famed hypersaline lake of the dead sea.