The first thing to do here is to defeat some bad guys, and get as many coins as possible. In the process, you will find a cave lit by a torch, and you must change to Willie to jump up there to get the First Treasure Chest.

If you go all the way to right, you will see a sheer dropoff, but there is a ladder there. Jump down to a level below and get the Second Treasure Chest.

Willie is also helpful in the corner all the way to the right, where she can jump up to a ledge. From there, she can jump up to a railing, and jump a little out to get the Third Treasure Chest.

It is in this corner that you will find a vending machine that distributes dynamite. Take that and destroy all the shiny junk in the corner. From here, you can build a mine car.

Now that the cart is built, you need to repair the tracks. There is a long silver girder that you must pick up and lay down on a broken place in the tracks. There are two grey boxes that must be punched, and the pieces to repair the rest will be ready to be used. There is a wrench by these gray boxes, and it needs to be taken by one of the characters in order to repair the mine car, and move it down the track as far as it can go.

Go all the way over to the left where there is an elevator thing. Put Indy on that other thing and have another character wind up the spot with the key. Have Indy go to the whipping platform and go to the other side. He will eventually come to a lever, that when pulled, brings down a ladder so Willie and Short Round can come join him. He then needs to jump on the scissor lift thing, and as it descends, the mine car will go up. All three characters need to be on that thing, and if necessary, switch characters until all are on it.

Once the mine cart goes all the way to the next level, it will lock into place. You must go around the other side and climb the ladder to get to it. Push the mine cart, and it will smash through an area, which will begin the next level.