Animating to a Sine Wave?

Well, it depends on how you animate the water. If you just give it a height h at time t then a sine wave should work perfect. You just substitute h for the equation Amplitute * sin(angular_freq * t + angular_offset) + height_offset

So if you wanted the wave to fluctuate between a height 1 and 11 you'd give it an amplitude of ( (11-1)/2 ) and a height_offset of 6 (-Amplitude + height_offset = 1 implies height_offset = 1+Amplitude = 6). If you wanted the wave to repeat its cycle every 10 seconds, that gives it a frequency of 1/10. However, we want angular frequency which equals 2*Pi*f. angular_offset is only important if you care whether the wave starts low, high, or in between so we'll ignore it. Your equations becomes:

height = 5 * sin( 2 * Pi * (1 / 10) * t ) + 6

t is in seconds (and should be a floating type as you'll call this multiple times a second).

Hope that helps.