Vandals have badly damaged a Department of Conservation (DOC) hut in Shallow Bay in the Fiordland National Park.
The hut's floorboards were taken to be used as firewood and the fireplace filled up with broken bottles, according to a DOC statement.
The department's Te Anau Principal Ranger Grant Tremain said the vandalism is an example of hugely disappointing behaviour in this area.
"Shallow Bay Hut is a wee gem of a hut and has been around since the late 1950s," he said.
"The hut is an easy one and a half hour walk from Rainbow Reach, so it's great for families to visit on day trips or stay overnight. It's also easily accessible by boat, being located right on the edge of Lake Manapouri.
"It's frustrating that one group of idiots can ruin the hut for everyone else."
Nearby on the Kepler Track, the Moturau Hut toilet block - which has the water supply turned off during winter - had a door kicked in and human excrement deposited in the bowl.
Tremain described this act as "disgusting and lazy".
"The toilet block is kept locked and water turned off for winter to reduce the risk of pipes freezing and bursting, but the nearby pit long-drop toilet is well signposted," he said.
"It's important people poo in a loo when they're available, but please don't kick in locked doors and leave nasty surprises for the next people to clean up."
Just three years ago, nearby Freeman Burn Hut was also severely damaged.
Tremain said he is keen to hear from anyone who might know who is responsible for the damage.
"I've had phone calls from some very grumpy locals who cannot understand why others would damage huts in this way. All up, the repairs are estimated to cost at least $3000. This money comes from the public purse so ultimately the taxpayer is affected by vandalism to DOC huts."