It was a Japanese colony and a battle zone during World War II. the Seabees, originally called the Bobcat detachment, saw first-blood there.
An island owned by Denmark.
The French Polynesia own the island of Bora Bora!
Chile
Wake Island is a US territory, I think.
Fiji is a country in the South Pacific. It got its Independence from United Kingdom in 1970. It is owned by the Native Fijians who are Melanesians with an admixture of Polynesian.
The island of Guadeloupe is owned by France
Tahiti, the Pacific island setting for his remake of "Mutiny on the Bounty" in which he costarred with his future ex-wife.
The islands that make up New Caledonia lie in the southwest Pacific Ocean, about 1,200 kilometres east of Australia and 1,500 kilometres northwest of New Zealand.
Gotland, administered by Sweden
Greenland is the largest island in the world, and it is owned by Denmark.
The most well-known island owned by Chile is Easter Island. They also the Juan Fernandez Islands and several other small islands in the Pacific.
The Pacific Ocean is not owned by any person or nation. Several nations have territory within the Pacific Ocean, but the majority of it is not "owned".