In any part of the world, seas are never still. Rarely, that too in some part of the world, seas are completely still. In fact, waves are the result of the wind blowing across the surface of the water.
The wind drags the water forward. which forms waves, faster the wind larger the waves. The height of a wave depends upon three factors like how hard the wind is blowing, how long the wind has been blowing, and the fetch. The word fetch means the length of the stretch of open water over which the wind blows. And winds are there due to the movement of sun and moon.