The Pacific Ocean region is an important location in the fiction of L. Frank Baum.
Most notably, the Land of Oz and its associated countries are located somewhere in the Pacific Basin. Dorothy Gale reaches Oz for the second time when she is swept overboard while sailing from the United States to Australia. (Ozma of Oz)
Horses appear to be consistently absent from Oz; only exotic magical versions of the animal (a sawhorse, a wishing horse, a giant horse, a thundercolt) ever appear. This is typical of Pacific islands and landmasses, where horses were unknown until Europeans introduced them.
Some fans have read details in the Oz books to indicate that the seasons in Oz are comparable to the seasons in the United States, which would indicate a setting for Oz in the North Pacific rather than the South Pacific.
So is the island of Delcapan. (The Girl from Oz)
The island of Pocofo is in the "South Seas." ("The Tiger's Eye")
Sam Steele and his companions find gold on an island in the North Pacific, while they are one their way to Alaska. Among their crew are two men from the real-world Sulu Islands, in the Philippines. (Sam Steele's Adventures on Land and Sea)
Rob Joslyn rescues two shipwrecked sailors from a desert island in the Pacific Ocean. (The Master Key)
Other desert islands in the Pacific are visited by Orissa Kane and her companion Sybil Cumberford. (The Flying Girl and Her Chum)
And obviously, Baum's 1911 juvenile novel The Boy Fortune Hunters in the South Seas is set in the Pacific region. Faytan is another pearl-rich island, like Sangoa or Pingaree.
It can also be noted that Birds of Paradise, native to New Guinea and nearby islands, play an important role in Policeman Bluejay.