Adding post proces volume to BP
https://answers.unrealengine.com/questions/435740/collision-on-post-process-volume.html
https://answers.unrealengine.com/questions/259253/adding-a-post-process-volume-to-a-blueprint.html
https://wiki.unrealengine.com/Swimmable_Water_Volume_Tutorial
https://wiki.unrealengine.com/index.php?title=Water_Shader_Tutorial
Notes:
- Project settings / rendering / lighting : Generate Mesch Distance Fields should be enabeld.
- Distance field does not work with skeleton, so you need to put a cilinder at the character.
http://www.worldofleveldesign.com/categories/ue4/materials-starter-content-water-instance.php