Gary Cronin usually lasted six weeks inside a diving capsule before he started seeing monsters. "I'd look in the mirror to shave and see horrible faces like a werewolf," says the 59-year-old Alaskan who began diving in Norway's North Sea oil fields in the early 1970s. "I knew then that I had to go to the surface."

Today, Cronin says his work caused more lasting harm: memory loss and spinal damage that have triggered thoughts of suicide. Cronin is one of about 4 000 divers who laid the foundations for the oil boom that transformed Norway into the world's second-richest country.

Nineteen are now suing the government, claiming they were crippled by living for weeks at a time at depths of up to 300 metres. The lawsuit may set a precedent for almost 140 other cases seeking more than 1 billion kroner (R1.48 billion) in damages, the divers' lawyer says.

"Norway has a fairy-tale image," says Cronin, a former US Navy Seal who lives in Oslo. "Underneath that, there's some pretty horrible things they've done in the name of wealth."

Testimony ended on May 6 in Oslo District Court. A decision was expected about September 1, said the court spokesperson, Irene Ramm.

Norway has reaped more than 5 trillion kroner from taxes, dividends and ownership of energy companies since it pumped the first oil in 1971, finance ministry figures show. Much of the money has been tucked away in the world's second-largest sovereign wealth fund, which has swelled to 1.95 trillion kroner.

The government says it has no legal responsibility for the divers' injuries because it did not employ them. It has paid about 2.5 million kroner to each of 200 former divers because of the state's "moral" obligations.

"The divers should direct their demands to the operators they were contracted to or the diving companies," says Christian Reusch, a lawyer representing the government.

StatoilHydro, Norway's largest oil company, has recognised its "moral responsibility" by paying a total of 75 million kroner to 113 divers whose health was damaged from 1965 to 1990, says spokesperson Ola Morten Aanestad. The Stavanger-based company has no legal liability because it followed government rules at all times, he says.

ConocoPhillips, which also pumped oil in Norway, declined to comment before the case is decided. Eirik Hauge, a spokesperson for Exxon Mobil, says the company's diving contractors complied with regulations, without giving details.

In 1991, Norway limited dives of more than 180 metres to 10 days, according to the Petroleum Safety Authority, which was unable to give details on earlier rules. Dives of more than 180 metres were barred in 2002.

Known risks

The pioneers dived to depths of 300 metres and lived underwater for as much as eight weeks at a time, putting them at increased risk of decompression sickness. If they returned to the surface too quickly, tiny bubbles released into the blood could cause lesions on the spine and brain.

Marius Reikeraas, the divers' lawyer, says the government did not tell the divers about the risks because of a shortage of workers. Norway disputes that claim, saying knowledge of diving risks has improved in the past 30 years.

"It's not like the government has been sitting on secret findings," says Reusch, the government lawyer.

When Norway discovered oil in 1969, petroleum had never been pumped from such depths. Divers were paid as much as $550 (R4 138.66) a day, 10 times what able seamen made, to help bring it to the surface.

In the early days, divers lived in steel chambers about 5 metres long and 2 metres wide that typically contained six bunk beds and a small table. They did not have enough room to stand up straight or take more than two steps.

The only recreation "was to go to the bottom of the sea and do a job", Cronin says.

Outside, the divers were chilled by the frigid water and dodged marine life such as wolf eels, seven-foot long creatures that crush shellfish with their teeth.

"Some jobs were shut down because the divers were afraid," Cronin says. "I've had big, strong guys quit on me."

About 350 to 400 divers with a "lasting connection" to Norway worked in the country's waters from 1965 to 1990, Reusch says. According to Tom Engh, who helped found the North Sea Divers Alliance, the number jumps to as many as 4 000 when you include those who worked for short periods.

Marit Groenning, a neurologist at Haukeland University Hospital in Bergen, examined 130 former divers as part of a government-commissioned study. A third had brain or spinal injuries, a third suffered from post-traumatic stress disorder, and others had lung damage.

Twenty-three pioneer divers have killed themselves, according to the Divers Alliance.

"We don't know of any other group of workers that has been under such extreme stress," Groenning says.

Preserving memories

Engh, now 62, says his career ended in 1978 when he sucked in talcum powder, used to preserve equipment, through a breathing hose that had not been properly cleaned.

Since his son was born 17 years ago, Engh has written down every conversation to protect them from his fading memory.

"Going to court feels like a personal victory," he says.

"What keeps me going is my promise to my son that I won't kill myself."