Instructions
Return to the area where you first entered the Northern Crater after sliding down the cliff and hopping down the stones three times. The crater's exit is the black area representing a cave opening at the top of your screen. You stood beside this area originally when you finished hopping down the stones.
Enter the black area. If done correctly, you should emerge on the left side of the screen at the crater rim, where you originally slid down the cliff. Walk to the brown and tan ladder-shaped rock to the right of the black area from which you just exited.
Climb the rock and then climb the rope ladder to return to the Highwind.