How can I make an ocean to fill go with my custom landscape?

Hey guys,

Im working on a large open world project in UE5 and I have hit a major road block. I have a large custom landscape that I just finished shaping but now I can find any way to place water in the landscape that will match with my landscape. The only way to make it work that I have found is with a custom water body but it still goes under my landscape and has no under water post process effects.

Has anybody out there found a solution to creating large oceans that will match up with your heightmap and terrain? I dont know why they made the Ocean body include an island. Seems kind of unintuitive to not have a body of water that naturally fits heightmaps. I hope that there is a solution outt here.

Thank you for the help.