Your ocean appears to
jitter or chatter along its horizon. If this occurs, you can smooth
or filter the flickering pixels along your ocean’s horizon.
To filter your ocean along its horizon
In the scene view, select the ocean that
appears to jitter along its horizon.
In the Attribute Editor,
select the oceanShader tab.
In the Ocean Attributes section,
increase Horizon Filter and then test
render your ocean’s simulation. Repeat this step until the jittering
along your ocean’s horizon disappears. See
Horizon Filter.