Descent of Pico de Teide via Pico Viejo (up via cable car, as the ascent path was closed due to black ice). Lesson: I don't do well at 4,000 m; perhaps I hadn't had time to acclimatise, but I had a splitting headache all day. The way back was longer than we thought and I was very tired. Nevertheless, an experience I wouldn't have wanted to miss. 392 m ascent.
