In the Water
Once you reach the top the mountain from using the lift you'll need to take the chain and attach it to the lift.
Then send the lift back down and it will break the dam.
After you're done with that head for the orange raft.
Give it a slight nudge and climb on being careful not to touch the water. Stand in the middle of the raft and look down, extend your arms and grab the raft. This way you can stay planted as the raft moves and also kind of 'steer' it.
As long as you're careful to not tip the raft over you should be fine, And by the time you reach the end the achievement will pop very quickly.If you need to restart
Restart the level from the beginning. Make your way across the water to where the end of the level tank is. Climb on top of it by swinging your arms
from side to side grabbing further every time. Once you're up, make your way to the top of the mountain by running up the path where the dam water flows.
Now just repeat the puzzle above.