My husband and I went climbing with Geo Extrem last weekend, near Montanejos in Castellon (half way to Teruel just off the N-234).
Although we went for the weekend and stayed in a hotel in Montanejos, it would have been easy to do as a day trip as we didn't meet until 09:30 on the Saturday and finished at 14:30. It took us just an hour and a half to get there from the centre of Valencia and cost 45 Euros each.
The company were excellent, very professional and our guide - Vincent -was really chatty and funny. He speaks a little English, enough for this kind of thing, and if you speak a little Spanish as well you'll be fine. He prefers small groups, and although some of the activities they offerneed a minimum of 4 people, others (like the climbing) only need 2. The equipment was all very new, top quality and he had a good attitude to safety. In the 4 hours we learnt alot, climbed 5 faces of different levels /difficulties and had a really wonderful time in the fresh air, hot sun (in December!) with amazing views over the stunning canyons and mountains in that area.
Although they do less activities in the winter, if you had something specific you wanted to do and enough people, he would definitely do it.
Their website is
http://www.geoextrem.com/On the Sunday we drove 20 minutes further north to Rubielos de Morawhich is a lovely Medieveal town, very well preserved/restored and a great place to just wander around.
Sue Cameselle