Where do you go after you defeat clayton in kingdom hearts?

Go past the new opening (where the rock wall was but disappeared during the fight with Clayton.) To the left, there will be a ramp made of rock with plants on it. Jump up this ramp and onto the ledge. Go to the left and you'll enter an area behind a waterfall. Climb up the rocks to the very top and you'll come to a place called ????. Enter it and you'll seal the keyhole.