A woman is feared dead after being taken by a crocodile in the Daintree National Park, north of Cairns in far north Queensland.

Key points: Woman was swimming in waist-deep water with friend at Thornton Beach about 10:30pm on Sunday

Woman was swimming in waist-deep water with friend at Thornton Beach about 10:30pm on Sunday Friend tried to grab the woman and drag her to safety

Friend tried to grab the woman and drag her to safety Whole of Cairns and up into Cape York known for large crocodiles, says expert

Cindy Waldron, 46, from Lithgow in New South Wales, was swimming with a friend at Thornton Beach near Cape Tribulation about 10:30pm on Sunday.

Senior Constable Russell Parker said the women were waist-deep in the water when one of them was taken by the crocodile.

"It's certainly very, very concerning at this stage and we would hold grave fears for the welfare of the woman," he said.

"Her 47-year-old friend tried to grab her and drag her to safety and she just wasn't able to do that.

"It would be very, very distressing for her.

"The 47-year-old then ran to a nearby business and raised the alarm, and from that point police and other authorities were advised.

"They had been walking along the beach and they've decided to go for a swim just in waist-deep water at Thornton Beach and probably a very nice, clear night, but obviously may not have been aware of the dangers."

Sorry, this video has expired Cindy Waldron is missing, feared dead, after a late night swim on a far north Queensland beach

Victim 'started to scream and was dragged into the water'

The victim's friend is being treated at Mossman Hospital. ( ABC News: Sharnie Kim )

The victim's friend is being treated for grazes and shock at the Mossman Hospital.

Neil Noble from the Queensland Ambulance Service said the 47-year-old woman had a graze on her arm that is believed to be from the crocodile.

"They felt a nudge and her partner started to scream and then was dragged into the water," he said.

Mr Noble said a local crocodile expert said a five-metre crocodile had been seen in area in the past few weeks.

"The whole of Cairns and up into the Cape is known for its large crocodiles," he said.

"Certainly one has to be very careful around our waterways. Stay well away from the water when you can, especially when you can't see.

"Just be very mindful that they are out there and that they can get you really quickly."

Authorities have been also searching along estuarine areas such as Cooper Creek. ( ABC News: Sharnie Kim )

Search includes shoreline, estuarine areas

Senior Constable Parker said a rescue helicopter was in the air last night using thermal imaging equipment to try to locate the woman, but could not find her.

A large-scale search began at first light this morning.

"We've got a forward command post set up at Thornton Beach," he said.

"We are utilising our own water police and land-based officers, as well was SES volunteers and so on, and we've got the SES boat in there as well."

Acting Inspector Ed Lukin said authorities and a rescue helicopter had been searching along the shoreline and estuarine areas such as Cooper Creek.

"The Department of Environment and Heritage Protection are here — they're providing expert assistance to us on crocodiles that may be of interest in this incident," he said.

He said the search would continue until dark.

Local resident Lee Randall said the area was a known crocodile habitat.

"There's a large male down at Cooper Creek, he's probably about four-and-a-bit metres, or even up to five metres," he said.

"As I said the other day, there's this little one just sitting here on the bank."

The local cafe has been closed to the public while rescuers use it as a command post.

The last fatal crocodile attack in the area was in 2009, when five-year-old Jeremy Doble was taken from a swamp near his home.