For a taste of adventure in Tenerife, visit Pico del Teide, the towering inactive volcano (3718 metre above sea level) situated in the Parque Nacional del Teide, which is a World Heritage Site, as desiged by UNESCO.
At the volcano, you can take a cable car to ride up toward the summit; it just takes 8 minutes to cover the thousand metre distance to the top. Be careful though, because the ride is not for the faint-hearted. From the cable car, enjoy a spectacular view of the volcano and the area around Las Canadas; once you reach the top, you'll be dropped off at a station 200 metre from the summit. From there, you'll find built-in paths for the most rewarding views of the park and island; the primary path leads east to the Mirador La Fortaleza, with views over the Orotava valley. The 2nd path will lead you to another viewpoint overlooking the 800-metre-wide crater; those who have permits can make the 30-minute climb to the summit of Pico del Teide.
From the station near the summit, panoramic views of El Hierro, Gran Canaria, La Palma, and La Gomera on a clear day can be seen; you might even see as far as Lanzarote and Fuerteventura.
During bad weather, heavy snowfall, and routine repairs, the cable car is not available for a few days, but you can always call ahead to check. During summer, go early in the morning to avoid the long queues of overexcited visitors.