The three missing divers, two course instructors and a course participant, had been among six people taking part in an advanced diving training programme in the submerged Maria Concordia magnesite mine on Sunday afternoon.
Two of them did not reappear on the surface after entering the water. The third man attempted to provide them with oxygen bottles, but he, too, disappeared in the depths of the mine, the PAP news agency reported.
Rescue divers resumed their search on Monday morning and shortly before noon a spokesman for the State Fire Service (PSP) in the nearby provincial capital Wrocław told reporters that two bodies had been found.
"I can't confirm if the bodies will be retrieved today as each dive diminishes visibility," the spokesman said.
He added that the third missing diver had not yet been located.
The rescue team comprises accomplished cave divers from all over Poland, including the southwestern city of Opole and the western Lubuskie and Wielkopolskie provinces, according to the State Fire Service.
There is also a diver from the Baltic city of Gdańsk in the north and rescue workers from the state-run mining group KGHM, firefighters said.