I worked as a deckhand on ships on the Arctic Ocean in my 20s, this was in the early 80s. The lack of distinction between sea and sky fascinated me. There were times we’d steam for days at a stretch between remote ports, which were tiny Inuit villages, where we’d sound and mark out the harbour.

There was little distinction between night and day as well, so that 2 in the morning looked little different from 2 in the afternoon. I leaned over the railing along the side of the ship staring into that utterly featureless scene, until a dramatic crack spread slowly across it.

These were glacier-scraped-smooth rocky islands far above the tree-line, and it was impossible to tell how far away they were or how large.