Andalucia: Nature sightseeing?

I'm going to have almost two weeks, all of which will be in Andalucia, and I expect that it will all be without a car. I'm interested in suggestions people may have for daytrips, accessible by bus/train or organized tour, that will provide for day hikes.

I'll probably only have time to do one or two, so if you could suggest what you consider to be the best dayhiking in Andalucia I'd appreciate it.

Thanks!
-- Ethan

I went last year to Grazalema Natural Park.
It is a wonderful place. This park was declared a Biosphere Reserve in 1977.
These mountains are in the province of Cádiz, near the city of Ronda.
They say it is the rainiest place in Spain, and here is the only place in the world where you can find forests of pinsapos (abies pinsapus). Well, you can also find them in the Sierra de las Nieves, near Grazalema.
Pinsapos are a kind of fir that only grow in Andalucia, in nothern Morocco there is a very similar variety of the same tree.

I think you have to make a reservation a long time before you visit the park, and in summer is not allowed to enter due to risk of fire.

http://www.grazalema.es/
http://www.cadiz-es.com/Grazalema/
http://en.wikipedia.org/wiki/Sierra_de_Grazalema_Natural_Park

The a couple that is on another travel website (I think MadridMan would not mine because he gives advice) call SlowTalk , they go by the name Clive and Sue and they are Nature sightseeing, Natural Images and this website Wild Hoildays

Post your question in the Rest of Europe, they might reply.

Bill