Forest Fortress

Forest Fortress is a secret Fortress found in Super Mario World. It can be accessed by completing the level Forest Secret Area in the Forest of Illusion. By completing this level, the player gains access to Star Road, located in front of Star World 4. Although officially part of the Forest of Illusion, it is situated out of the forest on the overworld map.

Normal exit
Mario starts out in a moving sidescrolling area. He finds Pillars throughout the area. After getting past the first Pillar, Mario also finds Grinders moving along dotted lines close to the ground. The player may have to use the Spin Jump to get past the obstacles. After progressing through the area, Mario also finds bottomless pits under the Grinders; however, these bottomless pits are completely covered by ! Blocks if Mario has activated them before the level. At the end of this area, Mario finds a door taking him to the next area in the fortress.

In the next area, Mario starts out on a platform above the lava. A Grinder immediately falls from a big rectangle platform at the top of the screen. Mario jumps over a pit full of lava, avoiding the Lava Bubbles that jump out. After climbing the next platform, Mario jumps into a small pit at the bottom of the screen, which contains two Grinders and a Triangular Block that Mario must use to climb out of the pit and progress through the level. Mario finds a Prize Block on the platform containing a power-up. Next, Mario must get a running start and jump across a pit of lava (with Lava Bubbles in it). The next platform is a long area made of a set of unbreakable gray blocks (and Lava Bubble and Grinders). Mario jumps across the blocks suspended above the ground, avoiding the Grinders and Lava Bubbles. When Mario reaches the end of the platform and jumps across the lava again, he lands on the last platform of the fortress. If Mario is on the part of the platform at the bottom of the screen, he finds a Triangular Block that helps him climb the wall and reach the boss door. Mario must, again, fight four Reznors on a set of four rotating platforms by hitting the underside of each platform.

Alternate boss door
The alternate boss door is a secret area that is hard to reach but contains enormous rewards. It can be accessed with Caped Mario, or by skillful Spin Jump on the Lava Bubbles. In order to go to the area, Mario must jump onto the row of blocks above the first boss door and reach a wide pit of lava with numerous Lava Bubbles. One way to cover the lava is to activate Caped Mario's gliding ability, flying consistently for enough time and avoiding Lava Bubble to reach the secret area. Another much more risky way is to spin jump on Lava Bubbles quickly and precisely. The area contains nine blocks with 1-Up Mushrooms and the second boss door. In the alternate boss door, the boss fight with the four Reznors is just the same as in the normal door. After defeating the Reznors, Mario gets the normal exit to the Star Road leading to Star World 4. As the alternate boss door does not count as a secret exit, the player is not required to take it to 100% complete the game.