( ( ( ( Ocean waves ) , ) ( ( winds , ) currents ) ) . )
(ROOT (NP (NP (NNP Ocean) (NNS waves)) (, ,) (NP (NP (NNS winds)) (, ,) (NP (NNS currents))) (. .)))
Ocean waves, winds, currents.
(ROOT (S (NP (NNP Ocean) (NNS waves)) (VP (VBP are) (ADVP (RB mainly)) (VP (VBN caused) (PP (IN by) (NP (NN wind))))) (. .)))