These mountains, being so high above sea level, are green and lush compared with the drier south, due to more rainfall and cloud moisture.
There was some cloud that day which made the views misty, but as it kept the temperature down we weren't complaining. The roads are winding and precipitous, as are the terraced fields, and we saw several of these zip-lines.
Don and Magda are standing on the edge of an almost sheer drop, but assuming the cage was for vegetables rather than for people, we didn't risk using it!
The barranco behind me was equally steep, although if I'd slipped, the cactus would possibly have broken my fall. Why is it that the steepness doesn't show up in photographs?
Across the road from where I was standing were these huge succulents clinging to the cliffside - each one the size of a small car.
We had lunch in Bar la Cueva in Chinamada - a little hamlet at the end of a very narrow road. We ordered a dish each which, when we saw the portion sizes, was a mistake. Delicious food, and the first time I have eaten gofio - a Canarian speciality.
There are several walks from there, notably to Pico de Ingles, but although the youngsters are experienced hikers, I certainly couldn't have made it that far. The little track I did explore was daunting enough!
Just round that corner I found myself looking across a deep barranco, in the centre of which was an isolated peak shaped like an icecream cone, totally covered in trees - truly spectacular.
There were lizards, quite large ones and not overly skittish,
and little houses that were half cave with fantastic views, and a tiny church.
Bod and Magda walked further than I did and didn't, this time, need rescuing.
A week earlier we had to drive to the middle of nowhere to collect them after they'd tackled a 6 kilometre hike that took them six hours. They had run out of water, despite taking as much as they could carry, and were so desperate that they drank from a standpipe in a field - they were lucky to get away without a bad tummy upset. Tenerife is an unforgiving place.
So if any of you haven't been to Tenerife yet, or have only seen the tourist places, put a trip to the Mercedes Mountians on your wish-list.