Eli has noted that there are not enough entries in his when the NW passage opens contest probably because the prize was only a foam blue bunny to place on your antenna. In order to encourage the laggards he now offers a genuine NASA Triana sticker, never used (sort of like the satellite).
We will follow Alastair
Since I get to choose I will propose this chart which is updated daily: http://polar.ncep.noaa.gov/seaice/hires/nh.xmlIn case of a tie, carrots at ten paces. Eli only got one of these. Don't complain, enter and it may be yours.
When there is a clear passage in pink from the Beaufort Sea to the Baffin Bay then we declare the NW Passage open. Otherwise we may have to wait for ESA to produce a report which the Telegraph picks up and then four weeks later appears in Wikipedia.