( ( ( ( ( The ( Southern Ocean ) ) -- ) ( ( a ( huge ( water mass ) ) ) ( surrounding ( ( the ( Antarctic continent ) ) ( that ( comprises ( one-tenth ( of ( ( the ( world 's ) ) oceans ) ) ) ) ) ) ) ) ) -- ) ( ( supports ( one ( of ( ( the ( ( most productive ) ( marine ecosystems ) ) ) ( on Earth ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NNP Southern) (NNP Ocean)) (: --) (NP (NP (DT a) (JJ huge) (NN water) (NN mass)) (VP (VBG surrounding) (NP (NP (DT the) (JJ Antarctic) (NN continent)) (SBAR (WHNP (WDT that)) (S (VP (VBZ comprises) (NP (NP (NN one-tenth)) (PP (IN of) (NP (NP (DT the) (NN world) (POS 's)) (NNS oceans)))))))))) (: --)) (VP (VBZ supports) (NP (NP (CD one)) (PP (IN of) (NP (NP (DT the) (ADJP (RBS most) (JJ productive)) (JJ marine) (NNS ecosystems)) (PP (IN on) (NP (NNP Earth))))))) (. .)))
The Southern Ocean -- a huge water mass surrounding the Antarctic continent that comprises one-tenth of the world's oceans -- supports one of the most productive marine ecosystems on Earth.
(ROOT (S (NP (NP (JJS Most)) (PP (IN of) (NP (NP (NN earth) (POS 's)) (NN water)))) (VP (VBZ is) (VP (VBN located) (PP (IN in) (NP (NNS oceans)))))))