The title says it all really, a slider in advanced intel that allows mission editors to control tide levels in their missions and also flood parts of maps like the salt lakes on Altis and the dried up canal/ditch/creek in Agia Marina on Stratis, possibly creating interesting scenarios.

An alternative to this would be for tides to automatically advance and recede at certain times of the day(like they do in reality)or add a script or module that allows players to create water at locations of their choosing(Which I believe was possible in ARMA 2/OA)