  We give an extremely short proof that the free-surface incompressible,
irrotational Euler equations with regular initial condition can form a finite
time singularity in 2D or 3D. Thus, we provide a simple view of the problem
studied by Castro, Cordoba, Fefferman, Gancedo, Lopez-Fernadez, Gomez-Serrano
and Coutand, Shkoller.
