Levels that use this gimmick involves the player being carried by Neena across the water. It's basically an autoscrolling level. During such level, the player has to dodge hazards and avoid being blocked by solid objects to keep him/herself from being dragged off-screen, which will cause instant death. Thankfully, Neena is immune to all hazards while carrying you in this kind of level.
In HTFA 5, you can make Neena jump by simply making your character jump and have her obtain pick-ups that are normally impossible to reach by your character (often inside solid objects).