National Park Service (NPS) rangers lead moderate to strenuous three- to five-hour hikes deep into the heart of the park on a daily basis during summer. The location varies from day to day; you can find the schedule at the Denali Visitor Center or online. Sign up at the center one or two days in advance and then reserve a shuttle ticket at the WAC.
Shuttles leave at 8am. Note that hiking is off trail, so be sure to have sturdy footwear and to pack rain gear, food and water. Rangers will turn away unprepared hikers. This is an all-day affair; the bus ride to the hiking departure point can take up to four hours, to hike for three to five hours, and then a similar-length bus ride back to the park entrance.