Police have not identified the victims yet. The incident took place off Betul beach in South Goa, 50 km from Panaji.
The boat, carrying ten passengers, all identified as Russian nationals, was on a Dolphin watching trip when it capsized at around 11 AM after being hit by a huge wave in the sea, an official of the state tourism department's lifeguard services said.
As the boat turned upside down, the three women got trapped under the boat and drowned.
The seven other passengers were rescued, he said.
The three bodies were later fished out and taken to the district hospital in Margao town for post mortem.
The MeT department here has advised people not to venture into the waters as the sea is presently rough.