I’m not saying a two-piece won’t allow you to swim, but the middle has been taken away! 

Through our middle (our core) we connect our arms and legs.  The core allows for great posture, is virtually tireless and our body rotation the ‘weight shift’ is our most economical source of power.

Visualise a dolphin.  One body working together, always streamlined.

Visualise a human.  Lots of independent body parts, always moving, changing shape.