There are three secret tunnels in the game. The first one is in the Gulliotine Museum in Horrorland Plaza. When you pick up the mop, you should see 2 buckets. The small one contains one of the 777 coins. The big one leads to a coin tunnel. Beware- this is the biggest tunnel in the game, with tons of grates, coins, and, you guest it- tons of beasts. Many traps lurk here, and they are traps to trap the beasts- they trap you!