An international effort to create a Census of Marine Life has been completed, increasing the number of counted and validated species to 201,206.
The £413m project got money and help from more than 600 groups, including various governments, private foundations, corporations, non-profits, universities, and even five high schools.
"We think that there are probably about 250,000 known species in the oceans, but we think that there are probably about a million or more in total, and that doesn't include the microbes," said Dr Paul Snelgrove, leader of the Census of Marine Life.
"We've very much undersampled the diversity of the oceans and we have a lot more work to do to really enumerate what's out there," said Snelgove, speaking at the Sealife London Aquarium.
But what scientists learned was much more than a number.
It was a sense of how closely life connects from one place to another and one species to another.
Speaking at a news conference at the Royal Institution of Great Britain Ian Poiner, Chairman of the Census Steering Committee, described how hundreds of scientists from over 80 countries worked together in the international effort to collect new information as well as consolidate existing information.
"We can make fundamental and major comments about ocean life past and ocean life present. And we can now use that knowledge to better forecast about ocean life into the future," Poiner said.
The census outlines the many, often bizarre and wonderful creatures spread across the world's oceans, as well as highlights the vast distances covered by migratory species.