This is in contrast of the age old water being a static entity, possibly even at a static height. Some way for this was paved when scripted sequences of water interacting in more interesting ways were done, but this is the culmination of that. Insert a body of mass and simulate how it flows, impedes movement, fills rooms and so forth.

Earliest form of this was witnessed in old side-scrollers where each pixel was like a grain of sand, and with water, a droplet of water, however huge.

Related:
* Wildfire
* Physics

Related: (water)
* Water waves
* Watery (water theme)
* Hydrologic cycle