Hi ,
Ehamloptiran has some good suggestions. They are the best option at the moment. There have been a number of requests here recently for water/ocean style systems in UE4 and we’ve heard the requests. It is definitely being discussed for what the best solution will be. Right now though, using these plugins provided by the community will get you there quicker!
If you have any questions on using UE4’s current features to start making a simple water material or particle system to make a splash feel free to ask and I can get you pointed in the right direction. 