Now Mario can head east through the newly opened path to find a Mushroom House (contains a Frog Suit for Mario) as well as a Wandering Hammer Brothers. where he should use the item to break the rock to his right. Then Mario should move across the map until he arrives at the top right screen.

You must first defeat the Wandering Boomerang Brother that carries the Hammer in a Treasure Chest. Warp Whistle Three The Third Whistle is found beyond the Dunes of World Two's desert.

Mario will fall into a closed room where a small Treasure Chest sits, holding the second Warp Whistle! Then Mario should run right until he can move no further before pressing UP to go through the door located there. Quickly run back to the left to build up the Speed Meter so Mario can fly, and then take flight straight up off the screen where you should hold RIGHT so Mario will fly over the wall to the right. Stomp the Dry Bones as Mario collects the Power-Up (it needs to be a Leaf to make next part of retrieval possible), and then run right to go past the door to the wall. Head right from the start, dodging through the obstacles of the Fortress until Mario arrives at an area with a Power-Up, a Dry Bones, and a door. Warp Whistle Two The second Whistle is to be found in the World One Fortress. Keep running right to enter into a hidden Mushroom House to gain access to the Whistle from a giant Treasure Box! Keep in mind that if you are jumping around behind the black scenery, you may jump the entrance to the Mushroom House, so just run along the ground). Now Mario has the ability to walk behind the scenery (including other blocks and bushes), so run to the right at top speed to get behind the black at the end of the level (this will be the same area as the Card Box). Get onto the White Platform (the only one in the level), duck down (hold DOWN), and after 5 seconds Mario will fall through the block. To gain access to it's hiding place Mario must go towards the end of the level to the point just short of a Para-Goomba that drops Micro-Goombas. Warp Whistle One The first Whistle to be found is located in World 1-3.

Super mario bros 3 walk through walls