Exo One

You need to first pick up the purple lightning bugs before trying.

Once you have picked up one, you need to prepare the lighting bug power thruster by holding and you need to keep holding it to keep it prepared. Then dive hard underneath the clouds / playing area using + . Once the sound barrier has been broken and the screen has flashed green etc. for a few seconds, you need to let go the trigger and keep holding to start rising back up towards the playing area. Once you have traveled upwards for a few seconds, now it is time to let go of and activate the power thrusters. If you do this correctly, the achievement unlocks after the power thrusting is over and you go below the sound barrier again. There is limited amount of flying space under the playing area, but enough for the achievement. So don't keep diving for to long or you'll hit the "floor".

It may not work immediately, but keep trying. Also, if the cutscene starts before you get your stuff done in this level, you need to hit start and restart the level. The level ends if the cutscene finishes and there is currently no level select in the game. Only way to get back is to play from the beginning again.