This is the first world of New Super Mario Bros. ULTIMATE. It has twelve levels: seven regular ones, two secret levels, a cannon, a tower, and a castle. It also has three Toad Houses: two red and one yellow. The first half of the world takes place on land and the part between the fortress and seventh level is around water. Peach's Castle can be accessed by clearing Lemmy's Castle. It provides hints that can be bought with Star Coins like in New Super Mario Bros. Wii. The tower boss is Boom Boom and the castle boss is Lemmy Koopa.
Mushroom Lake 1
This level is in a grassy field. Mario starts in a small forest that clears out into a few hills. Goombas and Koopas appear in this section. Next, there are some trees that Mario can climb on. This leads to an area with a lot of pipes that have Piranha Plants living inside. If Mario isn't careful, he can fall to his doom. There are some more hills and more typical enemies, followed by a wide gap where Mario has to use a P-Switch turning coins into blocks to get to the next part. This leads to the flagpole.
- Star Coin 1: Near the beginning, the Star Coin can be seen near the top of a hill. If Mario leaps off of it at the right place, he can snag the coin.
- Star Coin 2: The tall pipe with a Piranha Plant inside it has a Mini Pipe next to it. If Mini Mario enters it, he'll be taken to a secret room with the coin.
- Star Coin 3: Ice Mario is required for this or the Propeller Mushroom. In the P-Switch part, the coin can be seen below the second switch. Mario must have frozen an enemy previously and carried it there, where he should throw it from the platform, or simply flying into it.
Mushroom Lake 2
This level is underground. The player starts out in a small grassy plain. A green pipe sits there that leads to a cave. First, there are a few rising and lowering platforms over some gaps that Mario must cross. Next, Mario comes to a green and a blue pipe. The blue one leads him to a big maze of pipes that have a lot of Piranha Plants living inside. The green one takes him to a maze of Brick Blocks that Mario must cross. The paths rejoin soon after in a section above the ground that has a path of Mushroom platforms that Mario must cross and then the flagpole.
- Star Coin 1: Instead of going into the green pipe at the beginning, Mario must continue right into a spot that leads into pink pipe. This takes Mario into a secret room with some Buzzy Beetles and the coin.
- Star Coin 2: The player must take the green pipe path . Below where the exit pipe is, there will be a wide space with a single block. There is a P-Switch inside. After hitting it, Mario must head into a hole that has the Star Coin.
This level has a secret exit that can be used to skip every level in between this and 1-5. In the section with the Brick Block maze, Mario must stay as far down as possible. This leads him to a Cannon Pipe covered by some bricks Mario must ground-pound. The pipe shoots him out of the cave and into a Mushroom platform section that leads to the red flag.
- Star Coin 3: In the middle of the mushroom section, Mario will find the Star Coin high in the air. He must make a timed jump to reach it.
Mushroom Lake 3
This level is in the sky on many Mushroom platforms. Red ones make Mario bounce, green ones do nothing, blue ones rise as long as Mario is on it and pink ones sink when Mario is on it. Orange ones move to a place to a antoher Mario starts out in a cluster of green ones, with a few reds in between. This leads to a section with cannons where Mario can pick one of three routes to travel through. The first one takes him to another cannon section where Mario must shoot his way through a pipe maze near the ground. The second one, higher up, takes him to an area filled with Paratroopas. Mario cannot fall, but the Mushroom platforms are placed at steep angles which makes it impossible to backtrack. The last section is the only one with Star Coins while also being the hardest. Timed jumps are needed to get past the orange platforms and Paratroopas. They each have a pipe at the end that takes Mario to the flag.
This level has a secret exit that unlocks Lake Secret 1 and a red Toad House, hidden in the section with mushroom platforms. Near the ending pipe, Mario must make a timed jump to hit an invisible block containing a beanstalk. It is to the right of the last shroom platform and above two blocks. This takes Mario to a small Mushroom platform path with the red flag at the end.
Lake Secret 1
This level is in the water. It is more like a mini-game than regular levels and the path to get to the end requires a certain amount of points. The player starts by the shore, with Mushroom Lake 3 and Lake Fortress visible in the background. There is a red boat operated by a Toad, who asks Mario if he wants to ride with him. Mario says yes and the Toad tells him how to do tricks. After collecting at least 200 points, Toad opens up a path to the flagpole on the other side of the bay and Mario must travel through the short section on foot. All the Star Coins here are found in a secret cavern themed area which has a little spring flowing through it and has mainly Buzzy Beetles and Koopa Troopas.
- Star Coin 1: It is found right before the start. Mario must go straight to the left where there is a hole in the sand. Mario must go down the hole and go left, where the Star Coin is.
- Star Coin 2: In the middle of the cavern section by the checkpoint, the player should jump up above the flag revealing a hidden block. Mario should jump to the left from it, revealing an alcove that has the Star Coin.
- Star Coin 3: Right before the exit pipe, the player must pick up a Buzzy Beetle shell and throw it at one of the bricks right below the pipe, and then run and crouch under it to get to the coin. Breaking the brick can be done easily with a Super Leaf, Magic Wand, or Gold Flower.
This level allows the player to skip the fortress.
This level features the first boss fight of the game, being Lemmy Koopa. Mario starts near the bottom, which has an Ice Flower that can be used to defeat the Dry Bones army. The next section (after some moving platforms leading up) features Spike Pillars, but they move very slowly and shouldn't be any harm. After Mario reaches the checkpoint flag, he must climb a high wall that features disappearing platforms along with a small stream of lava flowing out. After this long section, the player reaches Lemmy, who tries to roll at Mario on his ball and jump on him. He is easy to dodge, as the arena is very simple. Three stomps will make him retreat.
Mushroom Lake 4
This level is on the shore. Mario starts out on a cliff near the water where a big waterslide made by some of the Red and Orange Toads are. Mario must go down it and head to the beach. The tide slowly comes in, briefly making some areas inaccessible. Mario comes to a pond. Mario must then head inside and swim across, avoiding the Cheep-Chomps and similar enemies, plus a giant Unagi at the end near the flagpole.
The secret exit in this level leads to Lake Secret 2.
Mushroom Lake 5
This level is underwater. It features lots of Cheep-Cheeps and Unagis, as in the previous level. Mario starts on the beach near some rocks, where a pipe takes him down. He must swim across, avoiding the Unagis, and head into another pipe. This takes him to an area with a Cheep-Chomp and some Bloopers. After swimming past them and some moving rocks, Mario reaches the Checkpoint Flag. After this, a swarm of Cheep-Cheeps comes, and Mario must head into a pipe quickly to avoid them. The pipe takes him to another area with a giant Unagi, who must be evaded to reach the pipe that goes to the flagpole.
Lake Secret 2
Mushroom Lake 6
This level is very similar to a Ghost House, but it takes place in a sunken ship. It also features the first appearance of the Mini Mushroom. Mario starts by the beach where Toad warns him that no one has ever come out alive. He shows Mario the path onto the deck and helps him on. Mario, thinking that Toad will help him, looks around for some items to help him, but finds that he has ditched him and decides to go alone. The opening section is on the top deck where Mario must find the correct door to get into the ship. Once inside, Mario will have to find trek the three decks for the exit. Each deck hosts different terrors, the most notable being the Boohemoth. When Mario gets out of the ship, he must swim across the sea to the shore where the flag is.
- Star Coin 1: On the top deck, Mario must wall jump up the masts to find the Star Coin in the crow's nest.
- Star Coin 2: After getting inside the ship, Mario must head left, where he will find a broken staircase covered in coins. Ignoring it, he must continue and hit a P-Switch. Heading back to the stairs, the coins have made a passageway. This takes Mario to a secret area on the deck by the lifeboats where the Star Coin is.
- Star Coin 3: The player needs to be Mini Mario for this. The player must find their way to the bottom deck, which is covered in water. If Mario goes right, he will see a tear in the hull that leads to a blue mini pipe. The pipe takes Mario to the sea bottom where a bunch of Bloopers live. Past them is the star coin and a path to the goal.
This level has a secret exit that unlocks the cannon. Going right at the first staircase to the right, the player must climb down and go left to the normal goal door. Instead of actually going through the door, Mario should ground-pound some nearby Brick Blocks that block a Mini Pipe. It takes Mario to a few pipes at the bottom of the sea. The left one shoots him out of the water next to the goal, the middle one shoots him to the top of the flag, and the one on the right (guarded by some Bloopers) takes him to a bonus room with many coins.
Mushroom Lake 7
This castle is very challenging. It features little lava, but there is a new challenge included into the game. Mario's timer starts with only thirty seconds, forcing Mario to complete it quickly. + Clocks are scattered all over, though, that grant Mario 10 seconds a piece. One at the end is huge and has 200 seconds on it, giving Mario time to fight the boss. The level consists of a lot of platforms in a vertical area, similar to a tower. Firebars are very common, along with Piranha Plants and Hammer Bros. The boss is Lemmy Koopa who will run around on his ball while throwing bombs at Mario, who must jump on him three times to defeat him.