Kill the Brute ahead the walk into the open area. Kill the Mantas and the Skaarj you encounter. Jump into the pond, and follow the underwater tunnel. When you emerge youll be in a courtyard inside the temple, kill the Manta and the Brute guarding the entry to the pool. Look carefully for the wall switch on one of the columns, it is simply a raised area and jump to activate it. Jump into the pool and get the Super Health Pack. Return to the courtyard and find the stone slab with the tiny floor trigger in front of it. Step on the trigger to lower the slab and fight the Brute in the next room. Jump on the lever to fill the pool and open a door to exit the level.