Tourism is very important to the Harz, although the prevalence of cheap air travel has led to a decline in recent years. There are many spa towns, and almost every village in the Harz and Harz Foreland caters to tourists. Well-known destinations are the Harz National Park and the Brocken, as well as the historic towns on the edge of the Harz. Concepts like the Western town, Pullman City Harz, or the rock operas on the Brocken are intended to also be particularly attractive to foreign tourists. The Harzer Verkehrsverband (HVV) is responsible for the marketing of the Harz to tourists.

In summer, the main activity in the Harz, by far, is walking. In recent years Nordic walking has become increasingly popular.

On several reservoirs in the Harz, a variety of water sports is permitted and, on a number of rivers originating in the Harz, there are opportunities for canoeing and other sports on white water sections. International canoe and kayak competitions take place on the Oker below the Oker Dam. The white water on this stretch of river is partly a result of the raised levels of discharge from the Oker Reservoir and so is largely independent of the weather.

Several hills provide a base for airborne activities, such as gliding and hang-gliding, notably the Rammelsberg near Goslar.

The Harz offers a range of climbing areas like, the Oker valley, with its rock outcrops (Klippen); the Adlerklippen being especially popular.The Harz has also developed in recent years into a popular mountain bike region, with 62 signed mountain bike routes and four bike parks with lift facilities in Braunlage, Hahnenklee, Schulenberg and Thale. The bike parks offer freeride, downhill and fourcross routes. Both the signed cycle paths and the bike parks are suitable for every level of cyclist.Roads in the Harz are used by racing bikes and touring bikes, despite their sometimes heavy use by lorries, because in the whole of North Germany there is no other region with such long, and in places very steep, descents and ascents. In addition, there are a large number of railway connections on the edge of the Harz which allow bicycles to be taken on trains.The Harz Mountain Rescue (Bergwacht Harz) service also operates in summer, rescuing people involved in accidents on difficult terrain.The mountains of the Harz were used in former times for long walks (e. g. by Johann Wolfgang von Goethe, Heinrich Heine and Hans Christian Andersen). An extensive network of footpaths is maintained today, especially by the Harz Club. In addition, there are several long distance paths (the Harz Witches' Trail, Kaiser Way, Karst Trail and Selke Valley Trail), as well as a trans-regional project, the Harzer Wandernadel, with 222 checkpoints and a range of walking badges that may be earned for various levels of achievement.

The Harz is also home to Germany's first naturist hiking trail, the Harzer Naturistenstieg.

In the Oker Valley and at Roßtrappe near Thale, there are rocks on the Hohneklippen (the Höllenklippe or the Feuerstein near Schierke, among several) that are used by climbers.