  We prove a continuation critereon for incompressible liquids with free
surface boundary. We combine the energy estimates of Christodoulou and Lindblad
with an analog of the estimate due to Beale, Kato, and Majda for the gradient
of the velocity in terms of the vorticity, and use this to show solution can be
continued so long as the second fundamental form and injectivity radius of the
free boundary, the vorticity, and one derivative of the velocity on the free
boundary remain bounded, assuming that the Taylor sign condition holds.
