Continue left until you reach a small structure.

Pull the small crate out from under the structure at ground level and use it to jump up to the platform above. Jump across to the rope nearby and slide down to the suspended platform below. Drop down to the left, and then jump across the pit to the right.

View Full-size

Pull the box out and use it to climb up (left). Drop down and jump over the pit beneath the girder (right).

When you reach the lake, jump onto the boat and let it carry you across the water until it lands on the opposite shore.