US Secretary of State John Kerry and State Councilor Yang Jeichi chaired the first meeting of a new oceans working group as the two nations moved into the third and final day of key annual strategic talks.
"Once again we're breaking new ground with respect to China and the United States's ability to find an area in which we can cooperate which has major significance ... For people everywhere," Kerry said.
Forum for the two uneasy partners to try to manage their increasingly complex ties.
China and the United States are two of the top fishing nations in the world, Kerry said, and also leaders in ocean science.
Also Read
"So we have a real opportunity here to be able to come together ... To deal with conserving and protecting the oceans," he said, adding it could be "a centerpiece in the newly defining relationship with China."
Yang agreed, saying the oceans were "a shared homeland of mankind, vital for our survival and development."
"The oceans are part of us, all of us," Kerry insisted, saying "we need to heed carefully the responsibilities that we have."
Beijing and Washington are working together to try to create a marine protected area in Antarctica in the Ross sea, he said, referencing one of the world's last true wildernesses.
Environmentalists say the Southern Ocean is home to more than 10,000 unique species, including penguins, whales and colossal squid.