If you continue driving along the TF24 past all the forests, suddenly the scenery really starts to change again and very dramatically this time. It becomes almost lunar as you begin to see remnants of millions of years of volcanic activity. It is truly amazing and unlike anything I have ever seen before.
Watch out for the viewpoint at La Crucita and stop here as the view is very special. You will see volcanic cones everywhere. These were actually formed when Teide erupted in the early 1700's.
A little way further along the road is an amazing rock formation called La Tarta. You can't miss it. Tarta apparently means "cake" and this is just like a huge cake, all full of different layers. The layers were actually formed all through the centuries by the different eruptions of the volcano.
We stopped for half an hour at the Visitor Centre at Portillo. It is definitely worthwhile taking some time out here. It is open every day between 9 and 4.30 and entrance is free. They have lots of interesting information and displays on the geology, climate, flora and fauna of the area. Many of the displays are interactive and hands-on. The information is in different languages. They also show a film about Teide, its formation and its eruptions. We found this fascinating and very educational. It is shown in different languages at different times. If you speak to the very helpful lady at the entrance, she will tell you when the film will be shown in your language.
Another interesting thing about this centre is the entrance - you actually walk through a reconstruction of a volcanic tube and there is a glass section you walk on over "molten" lava. It is not very high tech - but strangely you do feel quite unnerved as you walk across.