Abstract: A bottle having a container and a specially formed neck having a flange with downwardly sloping portion and which is spaced from the container to create a recess between the flange and the container. The bottle cap has an inner shell and an outer shell. A sealing surface moves longitudinally within the inner shell. The outer shell is preferably flexible and has prongs facing inwardly to move outwardly when the outer shell is compressed by a person's fingers. Other embodiments lack a separate inner shell and employ different operation of the prongs to retain the cap. In one case, rotation of the cap brings these prongs beneath a set of blind slots which engage the prongs and restrain their upward motion. Another embodiment allows the prongs to pass through slots to engage the underside of the flange. Further embodiments have a pressure release buttons built into the cap and a protective cap placed over the outer cap.