Yukon Delta, satellite image. The Yukon River rises in Canada and crosses the US state of Alaska before emptying into the Bering Sea at this delta, along with the Kuskokwim River. There are countless lakes, sloughs, and ponds formed and surrounded by the river's branching waterways. This is one of the largest river deltas in the world, protected as part of the Yukon Delta National Wildlife Refuge. Image data obtained by the Landsat 7 satellite on 22 September 2002.