Did you know that the original Super Mario Bros. contains a forbidden underwater level that you can enter—but never properly complete?

Known as World -1, or the Minus World, this strange looping level is one of the most famous glitches in video game history. Better still, you can visit it yourself in the original NES version of Super Mario Bros. and several releases based on it.

Hello, friends! It’s Tim here from Super Mayhem—awoo—and boy howdy, do we have some classic game-breaking action today!

In this guide, I’ll show you exactly how to reach the Minus World, explain why the glitch happens and reveal what makes this mysterious level impossible to escape.

What Is the Minus World?

The Minus World is a glitched underwater level hidden inside the original Super Mario Bros. for the Nintendo Entertainment System.

When Mario enters it, the level introduction displays:

WORLD -1

The level contains Bloopers, Cheep Cheeps and an underwater layout taken from another part of the game. However, reaching the exit pipe doesn’t complete the stage. Instead, Mario is sent straight back to the beginning.

You can continue swimming through the level for as long as your lives last, but there is no legitimate exit. Once you enter the Minus World, your normal playthrough is effectively over.

What You Need Before Attempting the Glitch

The Minus World glitch is performed near the end of World 1-2, shortly before the normal exit pipe.

Before attempting it, make sure Mario is either:

• Big Mario
• Fire Mario

Small Mario cannot break the ceiling bricks needed to set up the glitch.

I also strongly recommend creating a save state before attempting it. When playing through Nintendo Switch Online, you can use a suspend point instead.

There’s a good chance you’ll muck it up several times—just like I did—and having to replay World 1-1 and most of World 1-2 after every failed attempt gets old surprisingly quickly!

How to Enter Minus World in Super Mario Bros.

Step 1: Reach the Final Pipe in World 1-2

Continue through World 1-2 until you reach the pipe that normally takes Mario to the flagpole and the end of the level.

Do not enter the pipe.

Instead, jump on top of it and look at the row of ceiling bricks immediately to Mario’s left.

Step 2: Break the Ceiling Bricks

Break the second and third ceiling bricks away from the pipe, but leave the brick directly beside the pipe intact.

Some players only remove one brick, but I personally find that clearing two gives Mario a little more room and makes the setup easier.

You should now have one remaining brick positioned directly above the left side of the exit pipe.

Step 3: Reveal Part of the Warp Zone

Carefully move toward the right side of the screen until a tiny sliver of the first Warp Zone pipe becomes visible.

Do not move too far.

If the message “WELCOME TO WARP ZONE!” appears, the Warp Zone will load normally and the glitch will no longer work. You’ll need to restart the level or reload your save state.

The goal is to reveal just enough of the Warp Zone area to access its pipes without triggering the text.

Step 4: Clip Mario Through the Wall

Return to the remaining ceiling brick and stand underneath it while facing left.

Crouch, then jump backwards toward the right. You’re aiming Mario’s head at the bottom-left corner of the brick.

When performed correctly, Mario will partially clip into the block, slide through the wall and pass straight through the exit pipe.

This is easily the most difficult part of the glitch.

Mario will probably bonk his head against the brick while absolutely nothing happens several times. Don’t feel bad—it took me plenty of attempts to get it working while recording!

Try adjusting Mario’s position slightly and continue performing crouching backwards jumps until he slips through.

Step 5: Enter the Left Warp Zone Pipe

Once Mario has passed through the wall, move carefully to the right.

Do not scroll the screen any farther than necessary, as doing so may cause the Warp Zone to load properly.

Enter the left Warp Zone pipe, which would normally take Mario to World 4.

Bam! You have successfully entered the legendary Minus World.

Why Does the Minus World Glitch Happen?

The Minus World glitch occurs because Mario reaches the Warp Zone pipes before their destination information has loaded correctly.

Under normal circumstances, scrolling far enough into the room causes the “WELCOME TO WARP ZONE!” message to appear and assigns the correct destinations to the three pipes.

By clipping through the wall and entering the area early, Mario can access the pipes while they are still using unrelated destination data associated with the Warp Zone found in World 4-2.

The left and right pipes point to World 36, while the middle pipe points to World 5.

When Mario enters the left pipe, the game is technically attempting to send him to World 36-1. However, the graphic used to display the number 36 appears as a blank tile.

As a result, the level introduction only displays:

WORLD -1

That strange display is how the level became known as the Minus World.

Can You Complete the Minus World?

Unfortunately, no.

The Minus World reuses the underwater layout and enemies from World 7-2. The big difference is that the exit pipe has been assigned the wrong destination.

Instead of sending Mario to the end of the level, it returns him to the beginning of World -1.

Losing a life also places Mario back inside the Minus World. There is no secret exit, hidden block or alternative pipe that allows you to return to the main game.

The only ways to escape are to:

• Lose all of your remaining lives and receive a Game Over
• Reset the game
• Reload an earlier save state or suspend point

Once Mario enters World -1, his normal adventure to rescue Princess Peach is essentially over. Hopefully, she doesn’t mind waiting a little longer.

The Famicom Disk System Minus Worlds

Things become even stranger in the Japanese Famicom Disk System version of Super Mario Bros.

Rather than sending Mario into one endlessly looping underwater stage, the same basic glitch leads to a sequence of three different Minus World levels.

These areas contain bizarre combinations of level graphics, enemies and gameplay elements that were never intended to appear together. Unlike the NES Minus World, the Famicom Disk System sequence can eventually be completed.

This makes the Japanese version of the glitch an especially interesting example of how different releases of the same game can interpret corrupted or unintended level data in completely different ways.

The Legacy of World -1

The Minus World became so famous that later games began referencing it.

In Super Paper Mario, a character refers to The Underwhere as “World -1.” The brutally difficult platformer Super Meat Boy also contains glitch-themed stages and areas known as Minus Warp Zones.

What began as a simple programming error eventually became part of gaming culture.

It’s pretty impressive for a glitch caused by Mario entering a pipe before the game has finished loading its destination data!

Have You Visited the Minus World?

The Minus World remains one of the most memorable secrets in the original Super Mario Bros. Even though it cannot be completed, discovering it feels like stepping into a forbidden section of the Mushroom Kingdom that Nintendo never expected players to see.

Anyway, if you’ll excuse me, I need to ice my thumb because this took me far too long to perform and record. Being a little rusty at Mario 1 definitely didn’t help!

Check out the accompanying video to see the glitch in action, and subscribe to Super Mayhem for more retro gaming secrets, glitches, cheats and general video game chaos.

Have you ever entered the Minus World? Let me know when you first discovered this legendary glitch!

And with all that said, I’ll catch you soon, my friends.