Christmas Island is
1300 miles due
south of Hawaii.
That’s only about a
3-hour flight, but
Kiribati bends the
dateline to keep all its islands on the same
calendar, so travelers arrive a full day later. Part
of the Pacific’s Line Island chain, Christmas is
the world’s largest coral atoll, a full 45 miles
long and between 7 and 25 miles wide, although
lagoons make up nearly 2/3 of that area. What
land there is roughly forms a “Ç” that partially
encircles a central lagoon. That lagoon feeds
into the ocean on the island’s leeward side, its
entrance partly blocked by the Cook Island bird
sanctuary, which lies close to many dive sites.
The island was named after the day in 1777
  when Captain James Cook first happened upon
  it, but it remained uninhabited until the 1950s,
  when the British chose it for their nuclear
  weapons development project and induced a
  small Micronesian work force from the Gilbert
  Islands to relocate there. Once they’d tested
  their H-bomb nearby, the British pulled out,
  leaving behind a few Micronesians and a great
  deal of debris. Today the island’s 4400 residents
  are citizens of the Republic of Kiribati (pronounced
  kiri-BAHS).