The Police National Dive Squad has joined the search for missing Christchurch man Michael McGrath on Thursday.
Mr McGrath, 49, has been missing for 17 days and the dive squad has been called in to help search a number of locations around the Halswell area where Mr McGrath lived.
Police couldn't say where exactly they would be searching but did say "a number of water features" were of interest.
On Thursday afternoon the dive squad was seen searching through a lake directly opposite the house of a prison guard whose property is still under scene examination.
Pictures were released of Mr McGrath on Tuesday just two days before he went missing.
He was seen shopping at the New World Halswell on May 21 wearing a red t-shirt with a black polypropylene underneath with dark jeans on.