The whitewashed structure sits in the Xincun Port, a floating village where local residents seldom set foot on land, living in wooden cabins set up on rows of fishing rafts.
The hospital was founded by Frederick C. Yeh, a 32-year-old Chinese-American who graduated from medical school at Johns Hopkins University in the United States in 2005.
Planning on becoming a medical doctor, on a trip to his childhood home in Hainan in 2007 Yeh discovered sea turtles were being sold for meat and shells in local markets.
"We have plenty of food that's available to us, but these animals are endangered, and there are not many left," Yeh told China's state-run Xinhua news agency. "If we keep on eating them, eventually they will be extinct."
Deciding to change his career path, in 2008 Yeh founded Sea Turtle 911, a non-profit organization rescuing sea turtles across coastal regions in Hainan.
In the past four years, Yeh and a group of volunteers have saved more than 150 turtles, about 100 of which have been released back into the sea.
At his floating hospital, 14 "patients" are currently being treated, including a Hawksbill turtle that lost one of its limbs, a green turtle with a sunken shell, and many other injured or sick olive ridley sea turtles.
Yeh and his volunteers are offering training courses across Hainan, calling for children and their families to join his protection efforts.
"My plan is to stay in China and not go back to the Unites States until I see the end of the sea turtle market," he said. "I know that it will end at some point; hopefully, it will be the case that people will stop buying and there will be no market."