example of PhoenixFD ocean
This could be solved by switching to 3D displacement previously but not anymore
Same weird result I had with prosimplex.
Hi,
We have similar issues to this logged in our system.
We are working on improving the 2.5d displacement tessellation in v7, this should hopefully resolve this issue. In theory this should reach a daily build sometime in the near future 
Rowan
(Report ID=CRMAX-260)
Hi,
We have some displacement fixes lined up in the next daily build. It seems as though your issue is resolved by this: Displacement Fix | Corona Renderer
A few artifacts can still be seen, however these are totally resolved if you reduce the screen size (px) value to 1. Of course this uses a little more memory, but it still uses less memory than with the old displacement Displacement fix 1px vs 1.5 | Corona Renderer
Rowan