A spokesman for the Finnish Foreign ministry spokeswoman confirmed on Friday that two Finnish citizens had died in the Plura cave system, Norway's largest water-filled cave.
A team of 14 specialist police from Norway's Helgeland county were on Friday seeking to bring up the two bodies, which are apparently located 130m deep.
"It is a demanding operation that will take time," the police said in a press release.
The University Hospital of Northern Norway said on Friday that the three survivors were not seriously injured and were being treated for decompression sickness in a pressure vessel in Tromsø.
A Norwegian man died in the cave in 2006.