World 4 (AKA) Giant Land/Big Island is a kingdom of the Mushroom World in Super Mario Bros. 3. It is World 4 in the game, following World 3 and before World 5. This world contains six levels, three Sledge Bros., two Fortresses, two Spade Panels, four Toad House, and a Mushroom King's palace. Everything in this world is huge, including the ? Blocks, some Piranha Plants and Goombas, hence the name. Power-ups, Cheep-Cheeps, Spinies, Buzzy Beetles, Venus Fire Traps, and Bullet Bills are exceptions to this and thus remain in their original size. The island is shaped like a giant Koopa Troopa.
This is the first level of world 4, and introduces many huge versions of otherwise regular enemies like Goombas or Koopa Troopas. However, their size does not improve their stamina or other physical stats, so they can just be defeated like their smaller counterparts. The player will also encounter some big ? Blocks, which can be hit just like normal ones. If Raccoon Mario flies up in the area with the waterfall, he can access a hidden area guarded by a Venus Fire Trap. This room features two Big Berthas and two 1-Up Mushrooms. The level is plain-themed.
This level is similar to the third and eighth level of Water Land. The whole stage rises up and sinks down frequently, so some parts of the stage may submerge occasionally. If Mario falls in the Water, a Cheep Cheep will come by and try to hurt him, so the player should get out as fast as possible. The Cheep Cheep can be defeated with a well-aimed Ice Block, but it will quickly pop back up again after a few moments, and it cannot be defeated permanently. The goal is reached through a Warp Pipe at the end of the level. If Mario collects at least 24 coins in this level, a White Toad House will be available.
This level introduces the Sledge Bros. which is just a bigger and green version of a regular Hammer Bro.. Just like their smaller versions, they throw hammers at Mario, but they are also capable of a shockwave-creating jump that will stun Mario, making it likelier to get hit by a hammer. After crossing a plains section, the player will get access to the second part of the level through a Warp Pipe. The second half features many Buzzy Beetles and Spinies, as well as some bottomless pits which have to be jumped over using a Paratroopa as stepping stone sometimes. If Raccoon Mario is to fly up about halfway through the level, he can access a hidden stretch with coins.
World 4-Fortress 1
The first fortress of Giant Land features a new type of enemy: The Hot Foots. These flame-like enemies lurk on top of candles, waiting for Mario to turn his back to them. When unobserved, they hop off of their resting place and follow Mario, until he turns around. Some Thwomps move horizontally and vertically. During his traverse of the fortress, Mario can uncover a secret underground section of the castle, filled with Boos and Dry Bones, through a Warp Pipe. At the end of the caste, Boom Boom awaits.
This level is similar to the underwater courses 3-1 and 3-5 of Water Land, but the environment looks enlarged to match with the theme of the overall world. Also, Lakitu appears in this level, throwing Spiny Eggs at Mario. The player has to dodge the Spiny eggs while navigating through the water. If the player gave the Frog Suit power to Mario before entering the level or with a bit of timing, he can enter a pipe that ejects water and would otherwise wash him away. The pipe leads to a bonus area. Another Warp Pipe at the end of the level transports Mario to the goal.
This level features many Bill Blasters and also introduces a new projectile type, the Missile Bill. Unlike regular Bullet Bills, the red-colored Missile Bills will turn around if they are dodged and fly towards Mario once again. A block with a Magic Vine can be found in this level, which is accessible by bouncing off of a Missile Bill. Up the vine, Mario will find a Tanooki Suit, as well as a P-Switch which makes many coins appear. A pipe transports Mario to the level exit.
This level resembles the other plain-themed levels of this world, but it features magical doors which will alter the environment if entered. The player can swap between an enlarged version and a more regular version of the level. However, this provides no advantage and the level can be cleared in both versions. Some Starman and even some 1-Up Mushrooms are hidden at certain places throughout the course.
World 4-Fortress 2
The Donut Lifts here might be very dangerous. Mario must jump up and down on them to keep from falling. A secret is here after the lava stretch. In the narrow corridor, a block has a P-Switch inside. The Switch will expose some Silver Coins. In the middle of them, Up on the D-Pad should be pressed to enter a secret room (however, the Silver Coins need not be revealed in order to use the door, if the player knows the door's location). The platforms here are all different. The ones with arrows on them will automatically go a certain way, but the one with the exclamation point, whenever jumped on, will change direction. Skillful use of these and the many pipes will lead Mario to a pipe to a secret room, where, starting at the exit pipe, invisible blocks form a staircase to a block with a 1-Up. Afterward, a big ? Block has three 1-Ups, and Raccoon or Tanooki Mario can fly up to a little room above with quite a few coins. The exit pipe leads right to where Mario left off, and afterward is the fight with Boom Boom.
The airship of Iggy Koopa is largely fire-based. It is mainly composed of Rocket Engines which shoot flames towards the Mario bros. The player has to navigate them safely through the course without getting burned, by timely passing the traps in the instant they become inactive. A ? Block with a Super Leaf awaits at the end, as well as a gray pipe that leads to the boss battle.
In battle, Iggy Koopa utilizes a similar strategy as Larry Koopa and Morton Koopa Jr. by blasting energy rings from his Magic Wand. He is however a lot more jumpy and will bounce around more than his brothers. After his defeat, he drops the Magic Wand and the King of Giant Land is turned back to his previous form.
- The map resembles a Koopa Troopa.