Yesterday mates Cody Lye, Sam Llewellyn, Troy Peters and Danny Ryan emerged from the dense scrub unscathed, but only after spending more than 12 anxious hours awaiting rescue.

The group, all aged between 19 and 21, decided to head off on a short bushwalk in the national park on an otherwise uneventful Sunday afternoon.

But when they turned homewards after a dip at a popular swimming spot, Primbee man Danny Ryan, 19, said they found themselves on a different track.

"On the way back we took a detour and got a bit lost," he said.

As night began to close in, the disoriented friends were no closer to finding their way out of the bush, so Mr Ryan called police and was able to pass on their GPS co-ordinates from his iPhone.

Police rescue and POLAIR were deployed and the bushwalkers were located, however rough and dangerous terrain meant land crews were unable to reach the group.

For the friends that meant an uncomfortable night in the bush.

"We maybe got about 15 minutes sleep all up because we were all dressed in singlets and shorts, so it was pretty cold," Mr Ryan said.

When morning arrived the group started walking downhill and met the search party sent to find them.

Mr Ryan yesterday thanked emergency service crews for their efforts to rescue the group and said he was overwhelmed to see so many police and SES vehicles.

After their ordeal the teen said he was looking forward to getting home and having a sleep.

Lake Illawarra police Acting Inspector Gary Castles urged anyone trekking into the national park to ensure they are well prepared.

"The advice would be to wear adequate footwear and clothing and factor in when you're going into areas like this," he said.

"It's also a good idea to let people know where you are going and what time you plan to be back."

Police Rescue, ambulance Special Casualty Access Team, POLAIR, State Emergency Service and National Parks and Wildlife officers were involved in the rescue.