Move ahead to a pool of lava. Use Waterspout to create a spring of lava. Equip the Fire Tablet and hop onto the spring to ride up to the next level. Continue north and drop into a large pit of lava. There are passages on the left and right that lead to more lava. Both ways will lead to the fortress, but the left passage is recommended as there is a treasure chest there that contains a Crystal. On the right, the Treasure Chest there only has an useless Golden Peach. Nevertheless, look for springs to the north that Amaterasu can use to rise to the fortress above. Approach the doorway to the north and she will be attacked by a Red Ogre and a Blue Ogre. They are not hard to battle. See their links for strategy.