NASA recently posted an image of a nearly ice free North West Passage :
In mid-August 2016, the southern route through the Passage was nearly ice-free. For most of the year, the Northwest Passage is frozen and impassible. But during the summer months, the ice melts and breaks up to varying degrees. The Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured the top image of the Northwest Passage on August 9, 2016. A path of open water can be traced along most of the distance from the Amundsen Gulf to Baffin Bay.
Compared with 2013, there is a lot less ice. You can view a comparison here. I was interested to find out if this had happened before in recent history. NASA state that an ice strengthened ship could get through the southern route without too much trouble. Well, it turns out that a ship did just that in 1903 and 1905.
Captain Roald Amundsen, a Norwegian explorer, wrote about their voyage in Colliers Weekly (behind a paywall)
The ship did not face too much ice trouble on the Southern Route :
The passage they took was the exact same passage a ship today could take and at the same time of the year - August and September. They stayed on Gjoa Haven over the winter and the following year living and hunting with Eskimos. Then in August 1905, they sailed through a narrow rocky and icy passage to Amundsen Gulf.
I have shown the route they took overlaid on the recent August 2016 NASA image. It's precisely the same route that a ship could take today. This means there is little sign of warming in the Arctic since early 1900's and now.
With the Northwest Passage conquered, Amundsen sailed to the nearest telegraph station - he had heard from whalers that Norway and Sweden had become independent.