Roundfield and his wife were swimming off the southern tip of the island on Monday when they went beyond a protected reef area and got caught in rough water, said John Larmonie, a police spokesman for the police on the southern Caribbean island.
Roundfield, 59, managed to get his wife to some rocks where she was able to scramble to safety but he was then swept away in the current, Larmonie said. Search teams found his body about 90 minutes later trapped by rocks underwater.
"It's a real tragedy," he said. "He drowned saving his wife."
Julia Roundfield, a sister-in-law of the athlete, who lives in Detroit, said the family was still trying to get details of the incident.
"He was a real sweet guy," Julia Roundfield said. "He really was a sweetheart."
The player's wife, Bernie, was treated for shock after the incident.
A 6-foot-8 forward-centre out of Detroit, Roundfield played for Central Michigan in college and started his pro career with Indiana, which was then in the ABA. He played in the NBA for 11 seasons — besides the Pacers, he also had stints with Atlanta, Detroit and Washington and averaged 15.2 point per game for his NBA career.
Roundfield was selected as an All-Star in 1980, 1981 and 1982, when he was playing for the Hawks.
The drowning occurred near a popular snorkeling spot known as "Baby Beach," at the southeastern tip of the Dutch Caribbean island. The area just off the beach is generally considered safe but the water can become treacherous out beyond the reef in rough weather.
"It was a really bad day to go outside the reef," Larmonie said.
In August 2011, an American tourist, Gary Giordano of Gaithersburg, Maryland, reported that his companion, Robyn Gardner of Frederick, Maryland, disappeared while snorkeling in the same area. Police detained Giordano on suspicion of involvement in her death but he was released for lack of evidence and returned to the U.S.