This image shows the northern ice pack on Sept. 8, 2008, as observed by NASA's Aqua satellite. (NASA)

Retreating sea ice in the Arctic has made it possible to navigate around the entire northern ice pack, a first since satellite observations of the region began three decades ago, according to NASA.

As of the first week of September 2008, the extent of Arctic sea ice had still not fallen below the record low set in 2007, according to the U.S. space agency's Earth Observatory.

But it was enough to create open — though not entirely ice-free — waters all the way around the northern ice pack. The World Meteorological Organization defines "open waters" for the purposes of navigation as ice covering less than one-tenth of the surface.

NASA said it's the first time since satellites began recording sea ice levels in 1979 that it was possible to circumnavigate the entire ice pack, and probably the first time in half a century.

The route around the ice pack includes both the Northwest Passage through the islands of northern Canada and also the Northern Sea Route around the Russian coastline.

"This is the first recorded occurrence of the Northwest Passage and Northern Sea Route both being open at the same time," according to a press release from the U.S. National Ice Center.