A reflex that seems so unlikely that for years no one was aware of its existence. A baby suddenly immersed in water will seal of its lungs and begin to paddle and kick. The mouth may be open, but the epiglottis (cartilage and tissue which covers the larynx during swallowing, preventing food ‘going down the wrong way’) diverts water away from the lungs. The urge to breathe is suppressed, and immersed babies appear content in their watery environment. This ‘diving reflex’ disappears after six months or so, just when babies start to breathe through their mouth. Once this is gone, immersion in water does not come so naturally. But for our first six months, even before we can crawl, many of us are more comfortable underwater than we will ever be again. – Anthony Smith, The Human Body.