Ocean climbing my landscape..

I’m really hoping someone can help me.
I new to uefn and I’ve built mini islands, two of them are raised above sea level. One has a lake that leads to a river that “falls” into the ocean with a water fall. The ocean is drawn to the river and looks like its creeping up the cliff edges, going under the landscape i can see the ocean texture spreading up the landscape underneath. My other island has a mountain with too waterfalls and as soon as I put a lake at the top I get the same issue there too.
I’ve spent 3 days trying to sort this out and im gutted because my map is really coming on apart from this water issue.
Thank you.

Hi
If you are looking for realistic waterfalls for your project,
You can buy my easy waterfall pack.
Easy Waterfall Pack (works with UE 5.3 and higher) - Community / Showcase - Epic Developer Community Forums (unrealengine.com)