Hon May Rut Ngoai is located about 10km (six miles) south of Phu Quoc, Vietnam's largest island.
Nguyen Tien Hai, a senior Communist official in the area, said the authorities were still working to confirm the exact number of those who died as well as the survivors.
He is quoted by VnExpress as saying that the speedboat may have capsized due to heavy winds and high waves.
"The top priority is rescue, bringing all victims ashore and focusing all efforts on providing emergency care to those who are still alive," Hai said.
Indian Prime Minister Narendra Modi said he was "extremely saddened to learn about the tragic news of a boat accident involving Indian nationals" in Vietnam.
"My sincere condolences to the families who lost their loved ones. My prayers for the early recovery of the injured survivors," he wrote in a post on X.
The Indian embassy in Vietnam described the incident as "tragic", publishing the full list of the 32 Indian nationals who were on board the capsized boat.
The embassy also set up the telephone hotlines to "provide information and assistance to affected families".
