All Aboard the Terrain Train is the special level of World 2 in Yoshi's New Island. It can only be unlocked by collecting all 40 Smiley Flowers within World 2.
Layout
For almost the entire level, Blue Yoshi must ride on certain pieces of moving terrain over a bottomless pit while destroying some walls to getting crushed by the moving terrain and walls at one point goes into a vertical section where the goal ring is located at the end.
Smiley Flower Locations
Smiley Flower 1: Enclosed in some soft rock found at the beginning destroy the soft wall to obtain it.
Smiley Flower 2: Right before the vertical section of the level hit the winged cloud to reveal the Smiley Flower.
Smiley Flower 3: Found behind many soft rock walls on the right side in the vertical section.
Smiley Flower 4: After the moving terrain stops moving at the end destroy the spikes with an egg then jump on the slope to collect the flower.
Smiley Flower 5: Grab the key found in the first half of the level then open the locked door in the second half before the goal ring to end up in a bonus room make your way to the top to collect the flower.
Enemies