"It was really hard to learn that, in the oceans, there are so many nets that are doing so much harm out of sight," Giba, a three-times Olympic medallist with Brazil's volleyball team, said in a statement.
"As volleyball players, nets are at the centre of our game and of our joy."
About 640,000 tonnes of fishing equipment, which can trap marine wildlife, is found in the ocean every year.
Ghost Fishing, based in the Netherlands, has teams of divers working with the United Nations' Clean Seas campaign to combat marine plastic pollution.
"As divers, we care deeply about the oceans," Ghost Fishing CEO Pascal van Erp said.
"We understand just how ghost nets do a huge amount of harm to marine wildlife in places where only a tiny few can see that damage is being done."
(Reporting by Rohith Nair in Bengaluru, editing by Ed Osmond)
