Scientists on board the US Coast Guard Cutter Healy in the Beaufort Sea, northeast of Barrow, Alaska, finished collecting the mission's sea ice data and cruised south on July 20, 2011, through thin ice and ultimately into the open ocean. Corporations are now capitalizing on the melting of the ice by sending luxury cruise ships into the newly opened passageways. (Photo: NASA Goddard Space Flight Center)

This summer a luxury cruise ship was able to sail across the Arctic -- a feat previously impossible, now made possible by planetary warming. As Arctic summer sea ice melts away, this could mark the beginning for cruises in the extremely fragile, once-pristine Arctic ecosystem.