The victims, aged 52 and 16, from Hanoi, were visiting Phuket with their family for a business cum tourist trip, the Vietnam News Agency reported.
Le Trung Kien, an official in charge of citizens' protection at the Vietnamese embassy in Bangkok, said is coordinating with the victims' family and local authorities to bring their bodies back home and complete other procedures.
Suporn Muangkhai, a police investigator, said the drowning was reported by local rescuers at around 7:15 a.m., the Bangkok Post reported.
The women had been swept away from around 20 m from shore on Naithon beach in Thalang District, he added.
The police said there are red flags put up around the beach to warn people against entering the water due to strong winds and rough seas.
The victims reportedly ignored the flags, they said.