The first time you enter this small area, which is caught between parts of the Fingers of Stone, you'll take on the Eidolon Alexander with Hope, Lightning, and Fang. Afterward, the party will emerge from a cutscene on The Archylte Steppe. If you return to this area later, you can find a Rune Bracelet at the top of the small waterfall. Both Mission 08's and Mission 57's marks can be found in this area as well.