The Isar River ranks among Munich's greatest charms. The waters flow from the Tirol Alpine region of Austria. Allowed to run naturally, its tributaries are little islands edged with sand or pebble beaches, big flat rocks, and meadows of grass and wild flowers.
All kinds of people come to the water on warm summer days -- families with children, goth teens, gay couples, and gatherings of friends of all ages and ethnicities. Over barbecues and beer, they populate the riverside, bike the nearby trails, throw frisbies, read or doze, all mingling together without fuss or offense to one another.
Nude sunbathers turn golden brown, and activities on the gay cruising trails aren't hard to spot, among trees of the larger island just beyond the downriver footbridge. Aongside this, kids and dogs frolic, and lovers -- straight and gay -- get wrapped in private worlds of their own. This area is easily reached by U-Bahn; go to Thalkirchen station and follow the people with beach gear. Munich's famous zoo is nearby as well.
Fishing is popular too -- overnight fishing packages are offered by outfitters. Graylings and similar fish are abundant and a licence is required for all adults.
River rafting involves a gentle and leisurely float on a wooden raft, taking several hours, usually including a band, abundant food, and rambunctiousness like squirting passers-by on bridges above (bring water gun).
For more challenging action there is surfing on the Eisbach, a tributary of the Isar running directly through Englischer Garten. A standing wave is produced as water shoots from an underground tunnel at five meters per second and hits a breakwater. It's located next to the Haus der Kunst, now a museum, and rare surviving Nazi era building. Only one person can surf at a time, but polite young German surfers wait their turn, and aren't as territorial as those at "locals only" surf spots elsewhere. The water is cold, however. Pack a wetsuit or just enjoy the view. A calmer wave for beginners can be found at Thalkirchen Campground.