  We consider the interface problem between two incompressible and inviscid
fluids in the presence of surface tension. Following the geometric approach of
[Shatah,J.;Zeng,C. A priori estimates for Fluid Interface Problems. CPAM,
vol.16, no.6, June 2008] we show that solutions to this problem converge to
solutions of the free-boundary Euler equations in vacuum as one of the
densities goes to zero.
