Matacanes is the hard-edged adventure day out from Monterrey: a canyoning route in the Sierra Madre Oriental, usually approached through the mountain village of Potrero Redondo. The appeal is not a single viewpoint but the sequence of cold pools, waterfalls, jumps, rappels, and cave-like river passages that make the route one of Nuevo Leon's best-known outdoor trips.
Go with a proper guide unless you already have canyoning experience and local logistics sorted. The day is long, wet, and physical, and conditions can change after rain, but for active travellers it shows a wilder side of Monterrey than the museums and plazas in the centre.