Climbing the world’s largest trees requires more than standard monkey-bar skills. It involves ropes, harnesses, and aid tools similar to big-wall climbs. Which is to say tree climbing is serious business in Northern California, where rookies take 20-hour instructional courses in the Bay Area before setting out on their own. But you can get a taste in one day on a climb with Sam “Oak” Johnson, lead guide for Out on a Limb Tree Climbing ($300 for two). In Felton, seven miles north of Santa Cruz, ascend a 250-foot-tall redwood that has been standing for over 800 years—it’s more than 100 feet to the first limb. Afterward, come down to earth at the Dream Inn in Santa Cruz (doubles from $329), which has views over Monterey Bay, and make a weekend of it by jostling with locals at Cowell’s, the surf break right out front. (Board and wetsuit rentals, $35 per day at Cowell’s Surf Shop).