name an island in the said ocean.
New Guinea
Pacific Ocean
Melanesia, to the southwest, includes New Guinea, the world's second largest island after Greenland and by far the largest of the Pacific islands. 
what is horizon guyot? A presumably Cretaceous guyot how was it named? It is named after the research vessel where is it located? Mid-Pacific Mountains, Pacific Ocean
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Pacific Ocean [SEP] Landmasses and islands
The other main Melanesian groups from north to south are the Bismarck Archipelago, the Solomon Islands, Santa Cruz, Vanuatu, Fiji and New Caledonia. The largest area, Polynesia, stretching from Hawaii in the north to New Zealand in the south, also encompasses Tuvalu, Tokelau, Samoa, Tonga and the Kermadec Islands to the west, the Cook Islands, Society Islands and Austral Islands in the center, and the Marquesas Islands, Tuamotu, Mangareva Islands, and Easter Island to the east.