Forget about pulling that lever on the left side of the altar. Once you have the amulet just swim back and step on the button to raise the platforms. When they are up, use the amulet to slow down time and then run to the lower platform, hop up and jump to the next one and repeat to get all the way to the top.
next you go back near the entrance to this area and step on the button to lower the hands of the statue, and while they are lowered, use the amulet again to slow down time while you run to climb up on to the statue's hands.