To understand the behavior of waves at a fluid surface in configurations where the surface and the bottom meet (islands, beaches...), one encounters a difficulty : the presence in the bulk of the fluid of an edge, at the triple line. To solve the Cauchy problem, we need to study elliptic regularity in such domains, understand the linearized operator around an arbitrary solution, and construct an appropriate procedure to quasi-linearize the equations. Using those tools, I will present some a priori estimates, a first step to a local existence result.