The first comprehensive analysis of deep-sea dives has revealed that humans have only directly observed a tiny fraction 鈥� less than 0.001 per cent 鈥� of the global deep seafloor, leaving the vast majority of our planet unexplored.听
Oceans make up 71 per cent of Earth鈥檚 total surface area, and around 93 per cent of that area is deep seafloor, classed as seabed deeper than 200 metres. While much of this ocean region has been mapped using satellites and ship-mounted sonar, very little has been directly observed.
We only began exploring the deep sea in the 1950s, when submersible crafts capable of reaching the requisite depths were developed. Now, at US non-profit group Ocean Discovery League and her colleagues have analysed 43,681 records of deep-submergence activities since that time to assess how much of the deep seafloor has been directly studied. 听
Advertisement
The team estimated that between 2130 and 3823 square kilometres of seabed have been directly observed, an area roughly the same size as Rhode Island. That leaves 99.999 per cent of the deep seafloor unobserved. 鈥淚t really shows how little we know and how much there is still to understand,鈥� says Bell. 听
She points out that hydrothermal vents, which sustain an abundance of life in the deep sea, were only discovered in 1977 after they were first spotted near the Galapagos Islands by a deep-sea submersible. 鈥淣ow we know that you can have entire ecosystems that originate in darkness and feed off this hot mineral-rich water coming up out of the seafloor,鈥� she says.
The team also found that in 67 years of deep-sea dives, less than 20 per cent occurred in the high seas, otherwise known as international waters. Instead, deep-sea observations are dominated by exploration within the waters of the US, Japan and New Zealand, accounting for 71 per cent of all dives. Bell says this is the equivalent of entire continents being left unexplored.听
鈥淚f you have only explored the land of say, North America, Japan and New Zealand, how can you really know what is in the savannahs of Africa or the forests of South-East Asia,鈥� says Bell. 鈥淲e need a much more representative and less biased look at the deep seafloor.鈥� 听
Science Advances
