After discovering a few cuts and bruises, she turned her attention to what she was sitting on.
"There was definitely a small cow, so maybe a calf and a sheep and wetas and stuff like that. They were well dead, mainly just bones. It wasn't too bad, it was just cold - really, really cold."
The Nelson doctor had been out on Takaka Hill, near the Ngarua Caves, yesterday checking out a course for an orienteering event when she came across the sinkhole, which was much larger than she thought.
"We found this site where we were planning to put a [orienteering] control so went down to put my little tag there and lo and behold it turned into a bit bigger than a little depression."
The 44-year-old fell suddenly and couldn't grab anything to hold on to.
"I fell straight into the hole and screamed," she told the Herald soon after her rescue. Her friend Karen Monahan walked on ahead unaware of what had happened.
"Karen wandered off to check something. I don't know if she heard me scream or not, but she came back to look for me and heard me down there, so it's lucky I wasn't knocked out."
Dr Clendon checked herself for injuries and was amazed she wasn't badly hurt.
"I'm really lucky. I might need stitches to the knee, got a good bash to the head and some cuts and scrapes and bruises, but otherwise I'm all good."
Her knee was being x-rayed last night.
"The first thing I thought was, 'I haven't broken anything', then, 'That's a bit sore, so maybe I have'."
Dr Clendon was carrying a personal locator beacon in her backpack and set it off, and then put on some warm clothes. And while she waited for help, she bandaged her knee.
Leo Viersma was one of six cavers who came to her rescue. "A lot of the caving community have been out and about doing caving with the new explorations and stuff so there are very few left in Nelson, but we cobbled together six cavers."
Mr Viersma, who was involved in the 2007 rescue of another doctor, Michael Brewer, from a cave system on Takaka Hill, said one team member was sent down the tomo to assess the situation and put Dr Clendon in a harness.
Three lines were thrown down - one for the rescuer, the second for the haul system and the third as a backup. Mr Viersma called instructions from the surface but could not see anyone until they were 2m from the surface.
"I had to make sure it was all going right and nothing was getting caught up, as well as checking there was no slack in the line - so if something went wrong she wouldn't fall very far."
He said it took only about 20 minutes to get Dr Clendon out, but much longer to set up and dismantle all the rescue equipment.
- Andrew Koubaridis, NZ Herald
