Gary Coker and his daughter Kelsey wade into Rotorua's lakes most nights hoping to find "treasure". Instead they find live ammunition, old cellphones, rusty, jagged metal and broken glass.
Mr Coker, a conservationist, is appalled at the amount of "junk" discarded in the knee-deep shallows of the city's lakes.
"It's absolutely disgusting and so disrespectful. There are lead-based batteries leaching into the water, all sorts of metal, broken glass, plastic, you name it, it's there.
"You wouldn't think there would be live bullets out in our waters but there are tons of them... Thankfully I haven't found any needles, that's what I'm always worried about."
Mr Coker regularly shares photos on social media of the piles of rubbish he pulls from the water.
He said although it was disappointing to find so much rubbish, it was nice to be able to remove it and "do the proper thing with it" by recycling it.
"Lake Rotorua for example is not a place where people swim so the rubbish we find in there - which is a hell of a lot - is all from people throwing it in there."
Mr Coker said in one evening he would cover about 1km of water and drag up enough rubbish to fill a 10L bucket.
"When we go out with the aim to pick up rubbish like we did last weekend we would easily fill a wool sack with plastic, metal, glass, all that nasty stuff... It's just everywhere unfortunately.
"It is a rule of metal detecting to take any rubbish you find with you and leave no trace that you were there."
Mr Coker has been "treasure hunting" using a metal detector for about five years and said the amount of rubbish he had removed in that time was "mind-numbing".
"It's a hobby and Kelsey is really into it too and while we do pick up some treasures like gold rings and coins, the amount of rubbish we take away far outweighs the good stuff."
Bay of Plenty Regional Council Lakes Operations manager Andy Bruere said Mr Coker was an example of the "good sorts" that went above and beyond to do their part by collecting litter around our lakes.
He said one of the regional council's core functions was to maintain and improve the quality of the region's water resources.
"But we, the Rotorua community, all have a part to play in restoring and protecting our lakes including the simple things like picking up our rubbish when we are out on the lakes, cleaning our boats when we go from one lake to another to prevent pests from going where they haven't been before and changing the way we use pastoral land.
"A #loveourlakes campaign was launched in 2015 as well as a RTALP Facebook page to help mobilise our community to show love for our lakes, share photos and videos of how they love our lakes as well as pushing out the message that we are all part of the solution to protect them, everyone working together to protect our lakes."