The mission to map the world's ocean floors Seabeds hold the key to our understanding of climate change, but remain largely undocumented. Carl Court/Getty Images The ocean covers 71 per cent of the earth’s surface, but it is still something we know relatively little about. An oft-cited statistic in ocean science is that over 80 per cent of the ocean floor, an area roughly twice the surface area of Mars, is unmapped. This is surprising when you think about all the industries that depend on accurate information about the ocean, from shipping and coastguards to offshore wind farms and managing global fish stocks, to say nothing of the fundamental role it plays in understanding climate change.