Create ocean surface (vertical filling)

Dear Paraview community,

I have successfully imported and visualized bathymetric data for a given region of interested. I could “extrude” that (warp by scalar) so to create 3D bathyemtry and elevation.

What I now want to achieve, in this is where I seem to fail, is creating a volume of water (i.e. filling my domain), so to extend, vertically, from zero level, down to each bathymetry grid point. SOmething like this figure:

Any help is greatly appreciated. Thanks.

With the Nightly version of ParaView, the Warp By Scalar filter has an additional Generate Enclosure option that, when enabled, also creates the sides and bottom.