How can I make a tunnel underwater in a infinite ocean enviroment

Hello

I am using this to generate an infinite ocean : [Community Project] WIP Weather & Ocean Water Shader - Game Development - Unreal Engine Forums

I want to make a big underground tower that rises to the surface on a landscape. The landscape is surrounded by the Ocean generated by the above which is represented by just a file in my World Outliner (BP_Ocean).

The water and waves collide with the landscape - whenever I put a static mesh or a BSP in water (like a tunnel made from a hollowed BSP Cillinder - converted to a static mesh ) - the water just goes through the mesh.

I want to be able to add a cillinder in water and the water should collide with the exterior of the cillinder, leaving the interior dry. Is it possible in this way? (does it help if I have a cillinder mesh which has a bottom that can stop the water from going in ?)

Thanks!