What is Sigur Rós' new Norður Og Niður project all about?

Reps confirmed to Pitchfork that 'Norður Og Niður' isn't their upcoming record, the first since 2013's Kveikur, which they've been roadtesting on recent live dates and is produced by John Congleton. Is this new thing a single? An EP? Any new musical release would follow last year's ambitious Route One project, standalone single "Óveður", and a fresh mix of "Hoppípolla" for BBC documentary series Planet Earth II.

'Norður Og Niður' in English is 'North And Down' (so says Google Translate). The Icelandic troupe recently debuted a track titled "Niður" live in the US... a relation perhaps?

If you head to a mailing list page you're met with more riddles and no answers - if you sign up you get to download the picture (above) and a thank you email saying "soon...".

As well as the brief video and mailing list, Sigur Rós have been busy cryptically tweeting about the project.

#norðurogniður https://t.co/9xVKnY0utw pic.twitter.com/aO9wAxCNQp

— sigur rós (@sigurros) May 8, 2017

#everythingisgonetohell #northanddown #norðurogniður

— sigur rós (@sigurros) May 7, 2017

#allgonetohell https://t.co/qfm3m5JbK9

— sigur rós (@sigurros) May 7, 2017