I was fascinated with the lava rocks, so light and airy and colorful. I soon had a small collection of wildly colored rocks in my hand, which seemed to weight nothing and yet fill so much space. Shhh, don't tell anyone that I brought a few small ones home.
Hike #10 in Walk! La Palma hiking guide. Although, really, we only walked a fraction of this route as we were cold, tired hikers from our earlier walk that day. I'm sure the whole route is worth doing, but expect to fill your shoes with picon, or fine volcanic dust from a sliding descent!