There's hope a nasty vomiting and diarrhoea bug which has broken out on a busy walking circuit will pass quickly.

A group of 16 trampers has been helped out of the Nelson Lakes National Park on a water taxi, after some became ill.

They were on the 80 kilometre Travers-Sabine loop, which takes about five days to complete.

DOC Nelson Lakes Operations Manager John Wotherspoon said the ill trampers have been helped from the trail.

"They were water taxied out from Sabine Hut, which is at the southern end of Lake Rotoroa. There were a combination of those which were ill currently, those which were ill a few days ago and those which have not been affected. They're certainly pleased to be out of the park."

He said there are other isolated reports of people being unwell.

"We don't know what it is. Potentially it could be norovirus, or it could be something else," he said.

DOC has put extra hand sanitiser and bleach in huts along the loop.

"You just need to be extra careful. We're going to monitor the situation, and hopefully it will start to die down."