Brazilian and Paraguayan rescue teams have now retrieved eight bodies from the River Paraguay, where a boat capsized during a storm on Wednesday.
The Paraguayan vessel, Dream of the Pantanal, was carrying 11 Paraguayan crew and 16 Brazilian tourists.
Thirteen people had managed to swim ashore. Six are still missing and presumed dead.
The tourists had been on a fishing expedition to the Pantanal, one of the world's largest freshwater wetlands
The Pantanal, an area of amazing biodiversity, stretches across parts of Brazil, Paraguay and Bolivia and is popular with eco-tourists.
Many of the victims were friends who came from the same town in Brazil's southern Parana state.
They had rented the boat and had spent 10 days together, fishing in the Pantanal area.
The boat capsized less than 48 hours before the planned end of the excursion.
The Dream of the Pantanal was caught up in a heavy storm on Wednesday afternoon.
It sank between the towns of Carmelo Peralta in northern Paraguay and Porto Murtinho, in Brazil's Mato Grosso do Sul state.
Paraguayan and Brazilian Navy divers have been working together to locate the bodies.
"We found two more bodies today (Friday). We believe the other bodies are trapped inside the capsized vessel," Paraguayan official Amilcar Vera told the local Cardinal radio station.