Conservation groups have heralded the State Government's announcement of Camden Sound Marine Park as a significant win for the Kimberley.
But the Opposition is questioning why trawl fishing will still be allowed.
The park is the first of four to be created in the Kimberley and will cover 7,000 square kilometres of sea and coastline 300 kilometres north of Broome.
The park will cost the State Government $10 million over four years. The other parks will be created at Eighty Mile Beach, Roebuck Bay and the North Kimberley.
The Environment Minister Bill Marmion says a special zone will protect one of the world's biggest whale nurseries, with boats required to stay at least 500 metres away from the animals.
"In that particular special purpose zone, the whale zone we know there is about 1000 whales that calve there between June and November each year so this area will be protected, the conservation values will be protected,' he said.
Almost half the park will be closed to fishing trawlers, while about 20 per cent will be closed to other forms of commercial fishing.
Paul Gamblin from World Wildlife Fund says it is a huge win for conservation.
"We think levels of protection could be increased down the track, but overall we think this is a great plan," he said.
However, the Opposition's environment spokeswoman Sally Talbot disagrees.
"Trawling has no place in a marine park, so it's bitterly disappointing," she said.
"In an area like Camden Sounds, we would have expected an exclusion zone of about 70 per cent. Yet the Barnett Government will only close 23 per cent of the park to commercial fishing."
Ms Talbot says the Government should help the trawl sector move into trap and line fishery.
The state's Fishing Industry Association has questioned the government's commitment to compensating commercial fishermen.
About four north west companies will be banned from fishing commercially in some areas of the marine park.
The government promised compensation would be paid, if appropriate.
The association's chief executive Guy Leyland says those words imply that compensation is conditional.
"Ah we find that comment curious in regard to 'if appropriate'. Frankly, there's a statutory requirement for the government to pay compensation for affected commercial operators who are removed from these areas," he said.
The park will be formally created in the next few months.