The Oceania region includes the islands of Australia, New Zealand, Melanesia (including New Guinea), Micronesia and Polynesia (PRB 2013, UNSD 2013). At its furthest extents, Oceania encompasses approximately 63° of latitude, and 114° of longitude, with a land area of around 8.6 million km2; in mid-2013 the population of the region was 35 million with a population density of 4 km-2 (PRB 2013). However, only mainland Australia, Tasmania and some small islands in the Coral Sea, New Zealand, and the island of New Guinea are known to be naturally inhabited by freshwater crayfi sh, and will hereafter be considered as the Oceania region. As Australia, New Zealand and New Guinea cover such a large geographical area (~31 million km2) the region is remarkable for its range of climatic types, diverse climatic zones, numerous drivers of regional and local weather events, and various geological types and geological histories. The following sections briefl y outline these characteristics of the region.