After the swimmer returned to the reception without the woman, the man went down the track to look for her.
Unable to find her after 10 minutes, he realised "we were in trouble", and organised for emergency services to be called before resuming the search with an off-duty police officer, also at the wedding.
It was only then the men noticed the cliff, with an estimated 20m drop, and realised the woman had probably fallen.
Eventually the man saw the light from the woman's phone and found her ''inert'' in rosehip bushes. At that stage she had been unconscious for about 40 minutes.
"I figured the worst. I tried to get some response and then an arm moved and I realised that she was still alive."
She was flown to Southland Hospital where she had surgery for a broken pelvis.
The woman now faced a lengthy recovery, "but she's alive".
"It really is miraculous that she survived."
The man, who had not been drinking, did not believe anyone was to blame.
"She's only set off because she wanted to caution him and say it wasn't a very good idea.
"I don't believe that her actions were 'stupid' - stupid would be that she was aware there was a 20m cliff beside the path and she went off in a drunk state, regardless."