The following shortcut bypasses the trek through the tunnels near the mountain lake. If you use it, you'll miss one kill, a vulture, and the first 7 icicle traps for the "Public Service" achievement/trophy.

When you first emerge above the lake facing the HUT, turn around and safety drop to the slope below. Slide back and grab the edge but don't let go.

Instead, traverse to the right and pull up.

Turn around to face the water. Walk to the outer corner of the ledge. See the stone ledge with the large medi pack way down there across the lake? Aim just to the left of the highest point on that stone ledge.

Hop back from the corner then take a running jump across the water to land there.

Slide down and pick up the large medi pack (3).

From there, jump over to the snowy ledge against the cliff wall. Then climb the white ledges to the top of the canyon and get ready to confront a couple of enemies above.

If you fall in the water and don't want to reload, there's a small ledge roughly opposite the one with the medi pack where you can climb out of the water. An ice ladder there leads back up to the ledge below the entrance so you can try again.
Pick up the walkthrough at the section "HUT AND SNOWMOBILE."
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