Walk up to the box in the water and pull it left, look out for a rope hanging from a tree here. Place the box under the rope and use it to jump up.
Use the rope to swing up to the branch on the right. Turn around and jump up to the branch on the left. Run behind the tree and jump across to the branch stump further to the left. Jump up to the next branch on the right. Jump across the gap here and push the broken tree so that it falls in the water below.
Achievement/Trophy: Before making your way back down, from this platform you can run and jump to the left to grab a hard to see rope. Use this to swing up to a higher platform on the left, here pick up the egg for the achievement/trophy - Altitude is Attitude
Return to ground level and push the box back to the water.
Push both the box and the log as far as possible to the right without drowning and then jump on top of them and use the log to cross the water.
Hop up the other side. Continue right.

