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This was one of my first tasks I was hired to do a few years back. Ever sense then I've found substantially better ways to make this material better, and so I decided to upgrade and share it today - What makes this particular water material special is that it's actually entirely created out of Math, so it's not real water. It requires no special plug-ins, no Niagara Particle FX, no pre-created Box areas, no fluid simulation, and no custom colliders. It's mathematically generated water material that interacts with other objects using more math to simulate the collisions. This material is also based on world position which means you can apply it to any 3D mesh, be it a plane, cube,  sphere, or even an actor, and it will behave exactly the same way in all cases. All you need to do is apply it to whatever you want to look like water.

The Material instance is also quite flexible. You can customize and change just about everything about it down to the color, reflection, depth opacity, wave speed, collision ripples, and even the collision size. It can easily be adjusted to look more realistic if need be, but I hope it serves as a solid starting point for anyone trying to replicate the same effect! Thank you for your time - 

All the best,

-RS-