This review from The New Yorker seems to get the word mixed up. Daniel Wenger writes:
It was Vuong’s mother, a manicurist, who gave him his name. (He was born Vinh Quoc Vuong.) On a summer day at the nail salon, she told a customer that she wanted to go to the beach. She kept saying, “I want to go to the bitch,” Vuong told me. The customer suggested that she use the word “ocean” instead. Upon learning that the ocean is not a beach but a body of water that touches many countries—including Vietnam and the United States—she renamed her son.
The poet name is Vương, which means king. Dương, on the other hand, is ocean.