The water.dat is a data text file, the file contains, information about the water planes inside a boundary, water tri and rectangles in SA, normally is about the same size as the map boundary. The maximum amount of water planes is 1021. The water1.dat is not used by the game. But still can be found in; San Andreas/data/water1.dat
Water can only be defined for the normal map area (+/- 3000 on X and Y axis). This area is surrounded by a hard coded, infinite ocean, with a water surface at 0.0 and a seabed at -70.0 (Z axis).
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