Thanks!
Water wasn't a big part of the bigger plan so created something simple. The water is a trigger that applies an upward force to any object inside.
Then I placed some invisible triggers that a apply force in different directions to create the currents. They are actually the same component used in the water, but the force is sideways instead of up because the triggers are rotated.
I placed the triggers manually to mimic the currents. I wasn't interested in simulating the actual currents. Anyway, since this body of water doesn't change even a manual placement can be realistic enough.