Swim up and climb on the floating raft. Turn to face the entrance (the waterwheel should be on your right) and use the Grapple to catch the metal ring on the wall ahead. Press the Interact button to pull the raft through the water. When you reach the last pillar with the handholds on the right, press the Crouch (B) button to release the cable.

Jump to grab the first handhold, then jump up to grab the next above.

Jump up once more to grab the third handhold and jump to grab the wooden beam on the left.

Shimmy to the right.

Pull up on the platform and break the vase to get the Treasure (7/28).