You'll need 30 gems to unlock this level. We have 48 now.
This level takes place on a train moving through a blizzard. The Star is directly below you, but you cannot reach it. There are some crates on the roof of the caboose. In the third set of crates, you'll find the first gem. Approach from the left side. On the next car are some Biddybuds walking in circles. There are turnips in the centers of the rings, but you can ignore them. Up ahead are some Shy Guys patrolling a maze of crates. The plants ahead have coins. Go up the ladder to reach the train's engine. There's a Flaptor flying around. Walk around and go into the engine room. Blue Toad is there and he'll give you a Mushroom. Pull the nearby handle to sound the horn and make a 1-up Mushroom appear from the smokestack. Be sure to grab it. Go in the car directly behind the engine. There's a Shy Guy patrolling here as well. Go into the first cabin, then outside and up the ladder. Walk towards the back of the car and drop down on the blue Shy Guy. Go inside and through door to find the second gem. Climb up the stairs and move the touchstone block to exit. Go into the next car and you'll find many touchstones. Move them around so you can reach the ladder near the door you just went through. Make a path of the touchstones to reach the door. The third gem is behind the nearby bricks. Go into the caboose, a passenger car, and you'll see more Biddybuds. There are plants in the room. One of them contains a pickax. Return to the cargo car with the touchstones to get the third gem. Go back into the passenger car and go outside to find the Star.
Special Challenge: Collect the 1-up Mushroom.