World 4-1 (New Super Mario Bros. Wii)

World 4-1 is the first level of World 4 of New Super Mario Bros. Wii. This level introduces Big Urchins and is mostly submerged in water. Completing this level unlocks the world's Enemy Course and the levels World 4-2 and World 4-3.

Layout
This level begins on land, near a platform above the water with two ? Blocks above it. The player must then travel through a section of water, where Urchins, Cheep Cheeps, Mega Cheep-Cheeps, and a Piranha Plant are encountered. A piece of land with a Koopa Troopa, a Red Ring, and two ? Blocks are in the section. Afterward, two currents coming out of Warp Pipes are found, along with a wall that leads underwater. A group of Spiny Cheep Cheeps follows along with a platform with a ? Block containing a Star. The midway point then follows. The player must then go into the water, where more Urchins and Warp Pipe currents are located. A Roulette Block is hidden in the wall above. A section with Big Urchins follows, with Koopa Paratroopas flying above. After a Big Urchin with two Urchins, a structure made of bricks and ? Blocks is encountered. Underneath the last Big Urchin, there is a Warp Pipe leading to an area with three Clampys. After a section with more Urchins and currents, a Warp Pipe leading to an area with a Koopa Paratroopa and the pole is found.

Star Coins
A Penguin Suit is required for all three Star Coins.
 * Star Coin 1: The first Star Coin is floating high above the underwater Piranha Plant, which Mario and co. must freeze and use to jump up to the Star Coin.
 * Star Coin 2: Not far after the midway point, the second Star Coin is floating high-up in an opening, directly above an Urchin. Mario and co. must freeze the Urchin and use it to float to the surface and get within jumping reach of the Star Coin.
 * Star Coin 3: The third Star Coin is at the end of the level, atop the long sideways green Warp Pipe. Mario and co. must freeze the two final Urchins and use them as platforms to reach the Star Coin. Alternatively, Mario and co. can penguin slide across the water surface as fast as possible and jump to the Star Coin before the slide halts.