Big Kong is located at the upper right of the board. Kong's lair can be entered any time but you will not receive many points for this. To defeat Kong, you must first light all three bulbs below the Shaman. This will set up 6 triggers around his den. When you knock down all six of the triggers, the Tiki Guards will rise up and the fortress will be closed. By striking the guards repeatedly with the ball, they will sink down into the table. When all of the guards are knocked flat into the board, you must then shoot the ball into Kong's lair. He will then be defeated and you will receive a large bonus (about 5 million points). Two bonuses have been received by having multiball and shooting both balls into the lair in quick succession. Also the bonus is multiplied if you use a gold ball.
TIP: It usually takes three ball strikes to knock a guard down one level, but if the ball is launched from the catapult, the guard always lowers. Aiming the catapult between two guards and striking them both will lower both guards, but the ball tends to ricochet right between the flippers.