Pretty Beaches is a mod that improves the physics of water after sand blocks are broken. Normally water will trail and stop flowing after a few blocks are broken. This leads to continually filling those gaps with more and more water to make source blocks of water.
It’s a vastly more realistic interpretation of water but it does actually create water so it limits servers that may want to maintain limited water resources. But the filling aspect of this mod is a great addition and makes it super easy fill large holes. Normally the water will simply flow down and stop after a certain point.