In the Domain Advanced settings you need to adjust the "Realworld-size" (which I think is in metres) to something appropriate for the scene (unfortunately the standard GUI limits this value to 10) otherwise you end up with a noticeable "real water used on a scale model" look as seen in some Thunderbirds etc. episodes.

To get much beyond a domain resolution of 256 (when using auto gridlevels), you need to move to a 64bit version (if there is one).