Two fisherman have been rescued from chest-deep mud in crocodile territory off the Kimberley coast after their dinghy sank, leaving them unable to return to shore.

A helicopter raced against nightfall and an incoming tide to winch the men to safety late on Saturday afternoon, police said.

The men struck trouble when their dinghy sank in Roebuck Bay.

They attempted to reach the shore at Crab Creek, 20 kilometres from Broome, but were hampered by extremely muddy conditions which made the kilometre-long trek back to dry land impossible.

Members of the public saw the men showing signs of exhaustion about 700 metres from shore and notified authorities.

Fading sunlight limited rescue options

Police in Broome managed to make phone contact with one of the men and it became clear both were exhausted, one particularly so, officers said.

The option of a sea rescue was ruled out because there was not enough time before nightfall, so police organised for a local commercial rescue helicopter to assist.

The men were then rescued within 40 minutes, just before sunset.

Police said the men were chest deep in mud and showing signs of exhaustion when they were rescued. ( Supplied: Nigel Jackett )

Good fortune favours fishermen

WA Police issued a statement saying the men were lucky to have been rescued so quickly.

"With sunlight fading there was only a small window of opportunity to use the commercial rescue helicopter for a winching operation.

"Fortunately the helicopter crew were able to deploy rapidly and rescue the men," they said.

"Had that helicopter not been available it would have been a much more prolonged rescue operation, and with the hazards in place such as the mud and crocodiles there were many potential outcomes that could have been seen."

The area is a popular fishing spot for locals and visitors, but it is subject to extreme tides and muddy conditions.

Nigel Jackett was working at the local Broome Observatory where he witnessed the rescue.

"The tide had just turned, and that late in the day, with a quick incoming tide, they were lucky to get rescued," he said.

"I've seen a lot of people stuck in their boats when they get the tides wrong and they have to wait about six or eight hours before the tide changes.

"But I've never seen a boat sink before."