The forest where Hagrid shows Harry the dragons was set in Black Park, next to Pinewood Studios, while the first task of the Triwizard Tournament was filmed at the Steall Falls in Glen Nevis and Black Rock Gorge. For the second task, set in the Black Lake, the filmmakers tried a technique called dry for wet, where actors are suspended and wind is blown on them to simulate being underwater, but found "the hair didn't ondulate convincingly." The sequence was then filmed in a large underwater tank, and the actors took scuba diving lessons in preparation, under the supervision of stunt coordinator Greg Powell. Radcliffe underwent six months of training for the scene, and spent more than 40 hours underwater over the three weeks it took to film.