( ( In ( the ocean ) ) ( , ( waves ( ( are ( caused ( ( ( ( by wind ) or ) ( in ( some cases ) ) ) ( underground ( ( earthquakes or ) volcanoes ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (DT the) (NN ocean))) (, ,) (NP (NNS waves)) (VP (VBP are) (VP (VBN caused) (PP (PP (IN by) (NP (NN wind))) (CC or) (PP (IN in) (NP (DT some) (NNS cases))) (NP (JJ underground) (NNS earthquakes) (CC or) (NNS volcanoes))))) (. .)))
In the ocean, waves are caused by wind or in some cases underground earthquakes or volcanoes.
(ROOT (S (NP (NNP Ocean) (NNS waves)) (VP (VBP are) (ADVP (RB mainly)) (VP (VBN caused) (PP (IN by) (NP (NN wind))))) (. .)))