These sparsely populated tropical idylls are breathtaking in their beauty and remoteness. This sublime isolation inspired writers Tom Neale and Robert Dean Frisbie, who both lived as castaways on these far-flung coral atolls. Only the hardiest and most intrepid travellers ever make it to the Northern Group. Flights are few and mind-bogglingly expensive but, if you can surmount the financial and logistical challenges, the rewards are sublime.