Uniqueness wrought by isolation
The nature of an island is that it is left to develop in its own unique way. This is certainly true of Australia, the world's largest island (and smallest continent). Australia's striking landscape, which includes everything from lush rain forest to barren desert, is unlike any other in the world. This landscape is populated with the marsupials (such as kangaroos and koalas) that are so distinctly Australian that they are synonymous with the country in many people's minds. Culturally, Australia is quite unique as well. The Aboriginal cultures, which developed in isolation for 40,000 years, have intermixed with that of forcibly banished British convicts to create a uniquely Aussie worldview.
Each of the hundreds of islands of the Melanesian, Micronesian, and Polynesian island groups which together make up Oceania have also been able to develop in their own unique ways: New Zealand has its unparalleled natural beauties; Easter Island has its mysterious Moai statues; Tonga has its history as a never colonized independent monarchy; Fiji has its pristine beaches -- the list goes on and on, with no repetitions. A traveler who is simply interested in 'seeing the sites' can do fine backpacking through Europe. For the traveler who wants a truly unique experience all his or her own, Australia/ Oceania is the place to go.