From start, go down the spiral stairs to the right. At the bottom these two happy faces greet you. Shoot the cross (never mind religion now) to the left of them, and a secret door opens.

You will probably have had a small discussion with the natives, regarding ownership of the blue key. Follow the great tradition of Indiana Jones, and steal it anyway. Then take this water slide down (Uiiiiii!) and shoot the different textured bit of underwater wall. Guess what? A goodie!

The wall behind the gold key look a bit odd. Shoot it - get goodie. Or leave goodie and just shoot the damn wall on principle. Your choice. See if i care.

You have to do two separate things to get to the last secret. Shoot the red mark over the water pipe in the room with the blue key. Then shoot the cross over the grate in the gold key room. The bars will draw now, and you can go on a water slide from the gold-key to the blue-key rooms. Uiiiiii!

You could also act your age, and inspect the bottom of the pond in the gold-key room. Get trough the opening, and you will find the exit to the secret level "The Edge of Oblivion".