When the sun is overhead, Stanley figures he can only go for another hour before turning back. He can't see anything, but does notice a pool of water ahead. When he hurries towards it, he realizes it's a mirage. Stanley holds onto the sack from the sunflower seeds, just in case, and continues to walk towards the mountains. God's Thumb and the mountains look impossibly far away, though Stanley feels like the mountains are giving him the thumbs-up sign to encourage him on.
The mirage here represents the power of the natural world to alter humans' perceptions of it. Especially when combined with Stanley's sense that the mountains are urging him on, this suggests that nature itself, and possibly God, are leading him on a pre-prescribed journey towards something specific.
Stanley notices a large object on the lake. He can't figure out what it is, so he decides to head to the right and investigate it. He decides that the object will be his halfway point, and then he'll turn back. When he finally reaches it, he discovers that it's an old boat, half buried in the dirt. The boat's name is Mary Lou. Stanley notices a tunnel leading under the boat, large enough for a big animal. He hears something inside and tries to shout to scare the critter back in. However, the animal says "hey" back and Zero's hand pokes out.
The boat's name suggests that this boat is actually Sam's old boat. When Stanley discovers Zero hiding under it, it reads as though Sam himself is helping Zero along. This opens up the possibility that Stanley's journey doesn't just mirror that of Elya's; he may also be able to take actions that help atone for the atrocities committed in Green Lake, as well.