Please advise on my camera or scene setting

ibr_remote aka infinity10

I am using a combination of the ultramarine ocean underwater set and one of the GIS background props.  I wanted to make a sunken sci-fi city.  After I rendered using the default Whole Scene camera view, I find that I have some artifacts in the lower part of the render.  Please could someone advise me what I need to adjust to avoid this showing up.  Here is a half-size version of my render, using 3Delight (because ultramarine ocean doesn't render in iRay).