Compared to global seagrass meadows, coastal south-west Australian seagrass habitats experience high light, low nutrients, and high water movement. Despite these differences, similarities with other regions do exist and here we place the habitats of south-west Australia into a global context using comparative data. This paper, co-authored by IAN staff, is a product of an NCEAS synthesis on global seagrass trajectories and appears in a special 2007 issue of the Journal of Experimental Marine Biology and Ecology350: 21-45.