Concept: Action and Reaction

The Squirting Squid is a pool toy operated by hand and intended to be used by children ranging from five to fifteen.  The child pinches he squid's 'waist' (just before the tentacles), holds the head out of the water, and squeezes the head repeatedly.  When the squid is pressurized, the child aims it in the direction he or she wants it to go, and releases the the 'waist'.  The squid then jets away.

Internally, the squid consists of a rubber bulb in the head, which joins to a one-way valve that lets the bulb pump air through it into a rigid tank, but does not let air escape back into the bulb.  The tank is connected to a thin, deformable rubber tube ending in a nozzle.  The bulb is in the head of the squid, the tank is in its body, and the tube is at the 'waist'.  Pumping the bulb forces air into the tank, and the pressurized air cannot escape until the tube is no longer pinched shut.

The body of the squid would be soft rubber, as would the bulb and tube.  The valve and tank would be fairly soft plastic.  These parts should be cheap to manufacture or (in the case of the tube, bulb, valve, and tank) purchase.  Because the bulb and body would be rubber, the squid could not injure anyone or damage anything it struck.  The rubber body should also prevent the harder plastic tank from injuring the child.  Furthermore, the soft rubber exterior would protect the insides of the squid from damage.