Standard answer here is "there are no stupid questions, only stupid answers (or stupid answerers)". INish is right, you should give us an example so that we can see what you mare talking about. Anyway, let me guess. When you look onto water in the distance, the refelecting and non reflecting elements become very small and are laying close together. So anti-aliasing hat to balance high contrasts in neighboured pixels. This can be difficult and that is what you are seeing. Maybe you go to a higher anti-aliasing level (ultra) that lifts your rendering times very much or you try to cover that with other elements. Or you try to work on light or the water material to soften this effect. Whatever i am only guessing but maybe that helps.

One day your ship comes in - but you're at the airport.