Mighty No. 9

I found the best way to get this achievement is on the Water works level near the start when you climb 4 ladders you will come to a part where you free fall and there is electric kill zones ether side, if you go past the easy part and don't jump out of the first exit and go into the complicated part even if you die on the next obstacle your achievement will pop.

If you aren't sure what or where I am talking about will leave my video guide below.

To earn the Smooth Dive achievement, you must travel to right before the boss fight with Mighty No. 6. The location is an outside stretch of tower, after taking the Air Ship to the top, where there's a visible updraft.

Ascend the side of the tower and reach the top, where you would go to fight Mighty No. 6. Jump off and avoid all of the platforms, and floating ring holds, on the way down to the starting platform of this area.

100m is about the distance between the two openings and should unlock once reaching the ramp.