Farther from shore, away from the protection of hills and trees, the wind picks up momentum and gains strength, building ripples into wavelets, then larger waves, then, if the wind is strong enough, into whitecaps. By the time the waves reach the far shore and enter shallow water they are large enough to become breakers. Once acted upon by a generating force such as wind or a passing boat, large waves drive forward and gravity tries to fill every trough with a crest. This chasing of crest after trough is an effort to achieve the equilibrium of a flat surface. Gravity wants to create calm seas, which is why most waves larger than ripples are known as gravity waves.
Wind can produce several distinctive kinds of waves.
Ripples grow into wavelets, then into increasingly larger waves. They often occur in complex patterns, with waves of many sizes coming from several directions, creating confused, choppy, unpredictable seas. The roughest seas are typically composed of short, steep, sea waves produced by storms. Swell waves travel beyond the wind , either leaving the area where it is blowing or continuing on after the wind has ceased.