Right back at the top of the first screen of the crater there's a cave mouth. Go in. You'll be taken to the screen where you slid down from the Highwind into the crater. There's a 'ladder' of rock you can climb up. It doesn't get highlighted if you press 'select', so look sharp.

You can get unlimited Ribbons in the crater, by morphing Tonberries. Not easy, but worth it.

Good luck!