Koopa Canyon is the first level of World 2 in Yoshi's New Island as the name implies it is canyon inhabited by many Koopa Troopas the level is also very similar to Visit Koopa And Para-Koopa from Super Mario World 2: Yoshi's Island.
The first section has some Koopa Troopas and Koopa Paratroopas along with slabs that rumble before they fall when stood on continuing forward will lead to a gorge where a blue door is found at.
The second section contains a checkpoint ring along with the introduction of Metal Eggdozers from a pipe producing Metal Guys which can plow through enemies, destroy obstacles and traverse over hazards such as spikes.
The final section has falling stone blocks Yoshi must make it to the pipe at end before the stone blocks could crush him once all the stone blocks are in place Yoshi can use the last two stone blocks to reach the goal ring.
Smiley Flower Locations
Smiley Flower 1: In the area with the three Koopa Paratroopas Yoshi must swallow one of the Koopa Paratroopas then spit the shell out to obtain the Smiley Flower in the left opening.
Smiley Flower 2: In a tight tunnel before the field of Shy Guys spit the Koopa shell to collect it make sure not to land on the second falling slab since it blocks the opening making the Smiley Flower unobtainable.
Smiley Flower 3: Found in a tunnel after going through the pipe before the door to reach it Yoshi must jump off the two Koopa Paratroopas then enter the pipe once inside break the two soft rocks then swallow the Koopa Troopa then jump on the slab to make it fall once it is on the ground spit the shell in order to obtain the Smiley Flower.
Smiley Flower 4: Concealed behind a stairway made of stone slabs swallow the Metal Guy from the second pipe to produce a Metal Eggdozer after throwing the Metal Eggdozer follow it until it reaches the slabs then use the spring to collect the flower.
Smiley Flower 5: At the end of falling stone blocks area the Smiley Flower is plainly visible but Yoshi must be quick before the last stone blocks land over it.