This is the San Andreas version of the Flooded Liberty City mod, originally for GTA III.

Flooded tunnels and subway stations
-Some roads are flooded
-Ability to swim in the flood waters (GTA: SALC or United only)​​​​​​
-You can also sail on the flood waters...that is, if you're lucky!
-Pedestrians can be killed, and vehicles can be ruined
-Massive and dangerous waves (great for thunderstorms!!)