After you obtain the Spear of Destiny, grab the Statue of Fate (time slowing); and push it down the stairs. From there, push it to the edge of the water from the pathway you came. After you've done that, get to the other side of the path by running and swimming through the water.

Once you are on the other side, slow time (L1 + R1), but make sure you're in a straight line from the statue so you can activate the slowing of the time. Once the time is slowed, hurry up and backtrack to the large button floor, cross the water that is in the way by grappling it using R1.

When you are to the button floor, head through the door and gather your treasures, of that including the Urn of Olympus.