Super Mario Bros. 3/World 4

World 4 is called Big Island. Here, you'll find out everything has become giant! This includes not just the terrain, but also the enemies, so take special care here.

You start off on a small part at the left which is connected to the island with pipes. The map contains multiple pipes which have been colored here, pipes with the same color connect together.

If you didn't use the Hammer from World 3 (or from World 2, for that matter), go through the pipe at the beginning and use the hammer to break the rock to the left. You then gain access to a special red mushroom house which contains a Tanooki Suit! The two normal mushroom houses here feature the standard mushroom, leaf, flower choice. There's another red mushroom house at the top left, it allows you to choose between a leaf, a flower and another Tanooki Suit.

This map has Sledge Bros. patrolling. They are similar to the normal Hammer Bros., but can stomp on the ground to stun you, so jump in the air to avoid this. They award a Jugem's Cloud, a P-Wing and a starman.

4-1

 * If you're Raccoon or Tanooki Mario, fly straight up at the beginning of this level to land in a water pool. Go down the first pipe you see to enter a bonus area (see below).
 * Since the enemies are giant here, you need to take your jumping height into account much more than before. That giant Goomba is not as easy to defeat as in 1-1.
 * Stomp on the giant Koopa Troopa, then kick its shell against the ? block to the right to get a raccoon leaf.
 * The waterfall behind the first pit provides another opportunity to get to the bonus area if you're good at tapping A. You still need Raccoon Mario to fly over the pipes that block the path, though.
 * The next giant ? block has another raccoon leaf.
 * At the cloud platforms, you can use the shell of the first giant Koopa Troopa to take out the second one. Stomp on the last of the three giant Koopa Troopas, then take its shell, jump onto the pipe and kick it to the Piranha Plant at the next pipe to take it out.
 * The pipe at the end takes you to the ending area, which is empty apart from the goal card.

Bonus area

 * You only need to watch out for the Big Berthas here. The brick blocks here contain coins and two 1-up mushrooms. Exit using the right pipe to return in the water pool.

4-2

 * The terrain here moves up and down just like in 3-3 and 3-8. No Boss Bass is here, but instead Cheep-Cheep jumping out of the water. This doesn't make the level much easier though.
 * Remember that for giant Piranha Plants, you can stand right on the edge of the pipe without taking damage.
 * When you see ice blocks, kick one of them down to the giant ? block to get a raccoon leaf.
 * You can in fact stand on the giant clouds - they are not just scenery. This may help a bit in the part with the Piranha Plants shooting fireballs at you.
 * After a while you'll come across a P-Switch which transforms the brick blocks into coins. Step onto it when the terrain is up.
 * The small ? block contains a starman, which helps a lot in the upcoming stretch where infinite Cheep-Cheep will be flying at you.
 * Collecting 24 coins (i. e. every single one) unlocks the White Mushroom House. This isn't exactly difficult to do, you just need to watch for those Cheep-Cheep.

4-3

 * This level starts off with two Sledge Bros. Since you do not need to fight them, it's best to just pass them and get into the pipe, which leads into the underground area.
 * The underground level is similar to the pyramid level from world 2. The difference is that instead of a maze, there are large pits here.
 * On the first platform, jump onto the blocks to avoid the Buzzy Beetle. Jump from up there to make it over to the other side. Watch out for the ceiling Buzzy Beetle there.
 * The lone block on the small platform contains a raccoon leaf.
 * You'll encounter a new enemy here, namely Spinies. These cannot be jumped on, so beware.
 * After the first Spiny, if you are Raccoon or Tanooki Mario, fly up to get to a secret path with some coins.
 * When you see the wooden blocks, get on them and then jump at the leftmost brick block for a 1-up mushroom. To get it, run to the right until the next set of brick blocks.
 * The pipe at the end takes you to the ending area, which just has the goal card.

Part 1

 * At the beginning you'll encounter a new enemy: Hot Foot. These look like normal candles, but once you run past them, the flames walk off to chase you. They're rather similar to Boo Diddleys, in that regard. You'll see also Thwomps that don't fall down, but move horizontally.
 * At the beginning, just run forward past the candles, then drop down, the Thwomp can't catch you. Run to the next Thwomp, and once it moves, climb up the structure.
 * From the part where there are five pipes, you have two choices. You can either continue by sneaking through the Thwomps, this will lead you directly to Boom-Boom but is a bit risky. If you want the easy way, go down the middle pipe to get to part 2.

Part 2

 * Run down, jumping over the Dry Bones. The fifth block from the left has a Fire Flower.
 * The end looks like a dead end, but jump around to discover hidden blocks, which you can use to climb to the top. Watch for the Boo Diddley though which will chase you.
 * The pipe takes you back to part 1, but directly in front of Boom-Boom's lair. Stomp on him three times or feed him five fireballs to defeat him.

4-4

 * The first block you see contains a Fire Flower.
 * There's a bonus area in the lower left corner but normally, it is only accessible to Frog Mario due to a water current. A bug allows it to be accessed by any other Mario as well, though. Swim so you land on top of the ? block, then hold left and you should see Mario soar right through the water current, which allows you to enter the bonus area. (see below)
 * The Lakitu here will throw Spinies into the water. You may want to stay at the seabed to avoid them. However, there are no other enemies in this level, which makes it comparably easy.
 * The pipe at the end gets you to the ending area. Collect the goal card to end this level.
 * In Super Mario All-Stars, the water level has been changed to be consistent throughout the level. It's lower in the first part, but higher in the second part.

Bonus area

 * This bonus area has two secrets. First, swim up to the left cave. Jump at the single brick block here to uncover a P-Switch, step on it to make multiple coins appear in the room you're in.
 * After you're done with the silver coins, swim over to the right and hit the bottommost brick block. This reveals a second P-Switch. Collect some of the coins, then step on the P-Switch to transform the brick blocks at the top into coins, allowing you to collect them. Once you're done, take the pipe at the right, it takes you back to the level.

4-5

 * You will need a very precise jump to avoid the giant Green Para-Troopa jumping down the blocks. It is quite hard.
 * After the stairs, stomp on the giant Green Para-Troopa on the ground and kick its shell against the giant ? block to get a raccoon leaf.
 * Behind the pit, there's not just Bullet Bills, but also new Missile Bills which try to chase you. Since they can't move vertically they shouldn't be too much of an issue.
 * You can grab the Fire Flower if you want, but due to all the Bullet Bills, it may not be worth it.
 * After a small Piranha Plant, you should see a brick block above you. Jump to it to reveal a vine. To get to it, you must bounce off one of the nearby Missile Bills. Climb the vine to get to a bonus area (see below).
 * At the end, only jump down to go into the pipe if you're absolutely sure no Missile Bill will be following you. It leads into the ending area where you can grab the card.

Bonus area

 * The giant ? block contains a Tanooki Suit for you to collect. After that, jump on the P-Switch, then get out through the pipe to see multiple coins which you can use your newly gained Tanooki Suit to collect.

4-6
This level has doors that change between two versions, giant and normal-sized. There are also a few other differences between the versions.

Giant sized
This is how the level starts. In the rectangle of bricks, a 1-Up appears. The ? just after the door contains a Raccoon Leaf. Later in the level, there are 3 invisible bricks, all of which contain coins.

Normal sized
Entering a door will switch you between the versions of the level. In normal-sized mode, if you go to the left and see the same rectangle, it will contain a Starman. The ? just after the door contains a coin, and the 3 invisible bricks contain 2 coins and a 1-Up. Entering a door will take you back to the giant version.

Fortress
Be very careful early in this fortress; the platform is made of doughnut lifts. After a while will be a brick containing a P-switch. After getting it, you'll see some new coins surrounding an invisible doorway taking you to a secret room. Enter it and you'll notice a pipe maze where you can ride lifts, some of which can change direction, others cannot. At the top is a pipe taking you to a secret room with 9 coins and a 1-Up, and after that is another secret room with a large block with 3 1-Ups! After exiting the pipe, you can get to Boom Boom's room.

Airship
The king has been transformed into a dinosaur. All the cannons are Rocket Engines, and this ship has the Bolt Lift, which you can jump on several times to ride. At the end is a pipe that leads to Iggy Koopa, who you can stomp on 3 times and get a wand. If you kill Iggy and you still have the Tanooki Suit from 4-5, you'll get the message "Thank you kind raccoon, please tell me your name!" from the king. You'll get a message from Princess Toadstool with a P-wing.