Nintendo’s Secret Vault: The 15 Lost Levels of Super Mario Bros. 3
By a Retro Gaming Enthusiast | Hidden Gaming History

Super Mario Bros. 3 is widely considered one of the greatest video games ever made. It was released in 1988 in Japan. In 1990, it came to North America. The game dazzled players with its creative worlds. It featured inventive power-ups and polished level design. Most fans don’t know that buried deep inside the game’s code are 15 complete levels. These levels were hidden in plain sight for decades. Nintendo designed them but never intended for players to see.

These aren’t just scraps or half-finished ideas. They’re fully playable stages. They come complete with enemies and power-ups. Sometimes, there are entirely new gameplay mechanics. This includes enemies that never made it into the final game at all. Welcome to the lost levels of Super Mario Bros. 3.

How Were They Found?

The levels were left in the game’s memory. However, there is no map screen link pointing to them. This means there’s no way to access them through normal gameplay. The only reason they survived at all is likely because Nintendo had no way of knowing. They couldn’t foresee that a generation of dedicated fans would one day tear their cartridge apart, byte by byte. Fans would search for secrets.

The original method of accessing them involved entering specific Game Genie cheat codes. These codes redirected the game’s memory to load these hidden stages. This occurred instead of the normal first level. Today, the easiest way to explore them is through an IPS patch file. This file was created by The Mushroom Kingdom fan site. It organizes all 15 unused stages into a convenient level map for easy exploration.

A Tour Through the Vault
What follows is a look at what’s inside these forgotten stages. They reveal how Nintendo’s designers worked.

The Shoe Goomba Test Track
The first lost level appears to be a programmer’s sandbox for testing mechanics. It focuses on the Shoe Goomba. This is one of the most beloved and underused power-ups in the game. The only official stage featuring the rideable shoe is World 5-3. This fact makes this lost level a fascinating glimpse at a mechanic Nintendo clearly considered expanding. The level itself is crude: a two-floor layout with sparse enemies and pipes connecting the floors for no apparent reason. It reads less like a finished level and more like a testing environment.

The Creepy Coin Heaven
The second lost level is arguably one of the most memorable. It starts as a standard above-ground stage. Then, it transitions underground to an underwater swimming section. Finally, it deposits Mario into a bonus coin heaven. However, this heaven has a deeply unsettling green hue that feels entirely wrong. Unlike any coin heaven in the final game, this one also contains a chest with a Lakitu’s Cloud inside. This detail makes it feel like a place where the rules don’t quite apply.

The Athletic Challenge Level
Lost Level 3 bears a strong resemblance to World 7-3 in the final game. It features big hills and Note Blocks. These Note Blocks continuously spawn stars if Mario moves quickly enough. It feels like one of the more complete lost levels. It offers genuine difficulty. This includes lackatoos throwing spiny eggs, tricky jumps, and a beanstalk that leads absolutely nowhere. It even has a single, lonely coin floating in the sky, daring players to reach it.

The Proto World 1-5
Lost Level 4 is almost certainly an early prototype of World 1-5. It has the same underground cave feel. The same piranha plant-stuffed pipes are there. A brief above-ground section is in the middle. However, it’s smaller and less refined. It’s also missing the secret coin heaven. It even starts with what appears to be a “double door” concept that didn’t make it into the final game. Seeing it next to the finished World 1-5 is like comparing a rough sketch to a completed painting.

The Tanooki Suit Lab
Lost Level 5 is pure developer real estate. It is a sprawling room filled with different configurations of Tanooki Suit bonus chambers. These are those secret rooms accessed through giant Question Blocks. Rather than a playable stage, this looks like a testing ground. Designers laid out various room layouts side by side to compare them. Some of these designs made it into the final game in some form. Some wall pipes in this level will dump Mario back to the map screen. However, floor pipes lead to empty, floor-less voids. This results in instant death.

The Icy Mess
Lost Level 6 reads like a discarded concept from World 6, the ice world. It has Mario running across floating ice blocks, dodging Cheep Cheeps, Flame Chomps, and a bizarre mix of other enemies. The level is short and noticeably sloppy. A Koopa Paratroopa behaves in a deeply strange way. A Fire Snake inexplicably hops along ice blocks. This one feels like an experiment that was abandoned for good reason.

The Auto-Scrolling Water World (And Its Mysterious Enemies)
Lost Level 7 is widely considered the most exciting of the bunch. And it is for good reason. It’s a frantic auto-scrolling level. It alternates between land and water sections. It demands quick reflexes as Mario dodges Bloopers, Electros, and Cheep Cheeps. But the real discovery here is a completely new enemy type. They are tan-colored Cheep Cheeps that swim in packs of three. They bob up and down as they approach. These “Tan Cheep Cheeps” appear nowhere in the final game and were completely unknown until the lost levels were discovered. The level ends with a pair of Boomerang Bros — a challenging, inspired finale for a stage that never was.

Swimming Up Waterfalls
Lost Level 8 asks a simple question. What if Mario had to swim upward through a series of waterfalls? The answer, it turns out, is that it’s incredibly frustrating. The waterfalls are barely wider than Mario himself, making it trivially easy to fall off the sides. The one double-width waterfall in the level is noticeably more manageable. This suggests a mechanic that could have been successful with more development effort. The level ends anticlimactically in a blank blue desert where Mario can only collect a card. It’s easy to see why this one was cut.

The Floating Cloud Worlds and Green Parabeetles
Lost Levels 9 and 10 both feature a striking visual effect. The background clouds and Question Blocks float up and down. This gives the illusion that Mario is standing on a cloud drifting through the sky. Level 9 also introduces another enemy that never made the cut. These are green Parabeetles. They move faster than the red ones seen in the final game. Both levels are short and relatively easy, feeling more like proof-of-concept demos than finished stages.

The Prototype World 1 Stage
Lost Level 11 looks and feels like an early iteration of a World 1 stage. It is likely a scrapped level or an early design for World 1-6. With only Koopa Troopas and Goombas as enemies and an overall low difficulty, it feels unfinished. Some interesting ideas peek through. These include a two-lane section near the end and some coin-filled cloud platforms. However, the level needed considerably more work. It needed this before it could stand alongside the polished stages of the final game.

The Levels With No Exit
Lost Levels 12 and 13 are fascinatingly bare. Level 12 is short and sparse, with a small section at the end offering coins and a power-up — but no exit. The only way out is to get Mario killed. Level 13 is identical to Level 12, except every element has been shifted down by exactly one block. It reads as a designer nudging something slightly and saving both versions. Together, they’re a glimpse into the iterative, experimental nature of game development.

The Unfinished Cloud Concepts
Lost Levels 14 and 15 are both cloud-world concepts that were likely destined for World 5. Level 14 is extremely short. It has a few floating cloud pieces, Question Blocks, and coins. A long cloud platform stretches across the top of the level. A half-finished starry sky pattern appears to have been abandoned mid-design. Level 15 uses stacked clouds to create giant climbable platforms. It has a bullet bill cannon that never fires. There is no exit from the stage. Both levels feel like opening acts for something that never got written.

What Do the Lost Levels Tell Us?
Taken together, the 15 lost levels paint a vivid picture of Nintendo’s design process. Some are clearly test environments for mechanics — the Shoe Goomba sandbox, the Tanooki Suit lab. Others are prototype versions of levels. These prototypes made it into the final game in a more polished form, like the proto-World 1-5. A few introduced ideas. These included auto-scrolling water/land hybrids, waterfall swimming, and new enemy types. The ideas were either refined into something different or abandoned entirely.

What’s perhaps most striking is that a game as legendary and tightly constructed as Super Mario Bros. 3 still had this much material left on the cutting room floor. Fifteen full levels. Two entirely new enemy types. Mechanics that were tested and discarded. It’s a reminder that the polished masterpiece players loved was the result of enormous amounts of experimentation. There was a willingness to leave good ideas behind in pursuit of great ones.

Nintendo may not have intended for us to see any of this. We owe it to the dedication of the retro gaming community. It makes one of gaming’s greatest achievements feel even more remarkable.