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A group of teenagers who decided to carry out a nocturnal exploration of "a spooky old building" found themselves in the dock at Christchurch District Court today.

Liam Brian McMahon, unemployed, James Robert Hopman, a mechanic, Andrew Meredith Wilson, unemployed, and Lars Vind Thomsen, all aged 18, and Dex Michael Edwards, a 19-year-old builder, admitted being found without reasonable excuse in the derelict Christchurch Women's Hospital, the Christchurch Court News website reported.

The hospital in Colombo Street has been closed for years and is surrounded by a 2m fence.

Defence counsel Gilly Ferguson said the group had no intention of breaking the law, but had climbed through the fence to visit what they had heard was a spooky old building.

They were all sober, courteous, and apologetic when police found them in the building.

"It must have been pretty obvious that you were not entitled to be in this property, especially when you climbed through a hole in the fence to get inside," Judge David Holderness said.

He fined each of $350.

A young woman with the group was granted the diversion scheme to allow first offenders to avoid a conviction.