Canyoning (canyoneering in the United States, kloofing in South Africa) is a type of mountaineering that involves travelling in canyons using a variety of techniques that may include other outdoor activities such as walking, scrambling, climbing, jumping, abseiling (rappelling), and swimming.

Although non-technical descents such as hiking down a canyon (canyon hiking) are often referred to as canyoneering, the terms canyoning and canyoneering are more often associated with technical descents — those that require abseils (rappels) and ropework, technical climbing or down-climbing, technical jumps, and/or technical swims.

Canyoning is frequently done in remote and rugged settings and often requires navigational, route-finding, and other wilderness travel skills.

Canyons that are ideal for canyoning are often cut into the bedrock stone, forming narrow gorges with numerous drops, beautifully sculpted walls, and sometimes spectacular waterfalls. Most canyons are cut into limestone, sandstone, granite, or basalt, though other rock types are found. Canyons can be very easy or extremely difficult, though emphasis in the sport is usually on aesthetics and fun rather than pure difficulty. A wide variety of canyoning routes are found throughout the world, and canyoning is enjoyed by people of all ages and skill levels.

Canyoning gear includes climbing hardware, static or semi-static ropes, helmets, wetsuits, and specially designed shoes, packs, and rope bags. While canyoneers have used and adapted climbing, hiking, and river running gear for years, more and more specialized gear is invented and manufactured as canyoning popularity increases.