The road in this area is crawling with Humbabas and Juggernauts, both of which you may just be better off avoiding. Once you get to the entrance of Edenhall, you'll find more variety in enemies, as well as some Treasure. You'll see two particular Treasures sitting in plain sight on a glass floor. Normally, if you open either one, you cannot get the other. (In this case, you should take the Particle Accelerators on the left.) However, if you somehow manage to kill the Adamantoise outside before opening the Treasures, you can collect both.