ATVs are all-terrain vehicles used for traversing roadless/trackless terrain.
Several utility vehicle-type four-wheeled ATVs are used in Gold Rush. The film crew has been seen using them and getting stuck on them. (something like a cross between a pickup truck and a golf cart with ATV wheels) The Dakota Boys have a customized Kubota RTV900XT Mattracks utility vehicle ATV in season 4, equipped with tracks instead of tires.
The Hoffman Crew obtained off-road motorcycles for use in surveying and prospecting the Q.O.D. Claim. Todd Hoffman also road a 4-wheel regular ATV into the Andean Mountains instead of ride a horse, to examine a remote claim in a roadless area.