The Lemaire Channel is an eleven-kilometre strait on the Antarctic Peninsula, narrowed to 600 metres between cliffs of rock and ice a thousand metres high, and no ship can promise you a passage through it. When the pack jams the narrows the run is abandoned and the ship goes round the seaward side of Booth Island instead. A clear passage is luck, not an arrangement. When it is open, the engines come down to almost nothing. On the outer deck what you hear is the hull pushing brash ice aside, a sound like gravel running under the bow. The walls stand close enough on both sides that you spend the hour looking up rather than out. At the northern gate the twin Una Peaks, basalt towers capped with ice, rise straight from the water, the taller of them 747 metres. The water below is often mirror-still, and the cliffs stand upside down in it among grounded icebergs.
Zodiacs go down among the floes. With the outboards cut you drift, and the ice takes over: floes grinding against one another, meltwater running off the bergs. A seal lies close enough to hear breathing and to show the scars on its hide. In February and March humpback, minke and orca work the same water. Nowhere in the channel can be landed on, but its southern exit opens onto Petermann Island, where the zodiacs put you onto rock that gentoo penguins are already nesting on. Crouched low and still, you are taken for part of the landscape, and they carry on a few metres away. Late in the day the light never quite goes. The sun slides along behind the peaks instead of setting, and the shore ice holds its blue and amber for hours. The first ship to thread the channel was the Belgica, in 1898. She carried on south into the pack, and the ice closed around her for thirteen dark months. The crew lived on raw seal and penguin meat, a young Roald Amundsen among them, with no way out until the ice let go.