NSW Police divers have searched a dam on the mid-north coast for any trace of missing boy William Tyrrell, as the incoming commissioner promised "we're not going to give up".
"We need to find William and get this resolved," Deputy Commissioner Karen Webb said.
It's the 11th day of a renewed search for the three-year-old, who disappeared from his foster grandmother's home at Kendall in September 2014.
Police have been intensively searching around the home as well as nearby bushland, enduring a week of persistent rain.
A day after being named as the next commissioner, Ms Webb said the team of 30 police involved in the search had been joined on Wednesday by specialist police divers, who inspected a septic tank and a water tank on the Kendall property.
The divers donned wetsuits and scuba gear to search a small dam on Thursday.
Ms Webb says she's confident there will be a result in the case but it will take time.
"It's a long laborious search and obviously the weather conditions up there at the moment are unfavourable but police will pursue that no matter what," she told Sydney radio 2GB on Thursday.
"I'm confident this team will keep pursuing this until we get a result.
"We need to find William and get this resolved."
More than 15 tonnes of soil have been taken to a lab for analysis but Ms Webb said she was not aware of any DNA being detected.
"There's been miles and miles of material and many exhibits taken that will be examined but that takes time."
The search is expected to continue for at least another four weeks.
"We've got our best detectives up there," she said.