Selection of large amount of control points with x=0

Hi there,
I have a map of Rhode Island and I am trying to delete the ocean. Since most of the land is at such low elevation I am struggling with figuring out how to delete the ocean and not any of the land. Thanks in advance for your help.

Make a plane at z=0 (not sure why you refer to x=0…) and use that plane to trim the seabed?

Thanks for the suggestion! I am not sure why I didn’t think of that!

Courtney Reckord
Artist, creativity coach