Marine scientists in Hawaii are this week to make another expedition to explore the coral reefs around the mostly uninhabited northwestern islands of the archipelago.
On a just completed trip they made over 100 dives on the reefs, going to depths of up to 80 metres, using customised mixtures of nitrogen, oxyen and helium.
The lead scientist for the National Oceanic and Atmospheric Administration, Randy Kosaki, says this allowed them to see habitats not seen by humans before.
He says so far the divers have seen only a small portion of the 2,000 kilometres of reefs and, though it will take years, they aim to explore as much of it as possible.
"To try and find sites that are representative of much larger areas. Obviously one can't be everywhere all the time to conduct environmental monitoring, and so you would eventually pick sites that are representative of large swathes of habitat because you can't be anywhere, you monitor a few key sites that represent the larger system."