For the popular synchronous fireflies viewing, the park typically holds the lottery for parking passes over several days in late April and early May. The fireflies are usually active in late May to early June. Cost: $2.75 per vehicle, plus $1 per person for the trolley. More information: Sugarlands Visitors Center; 1-865-436-1200; nps.gov/grsm/learn/nature/fireflies.htm
Campers staying at Elkmont Campground can walk to the viewing site. The campground, 8 miles from Gatlinburg, Tenn., has 220 sites for tents and RVs. If you are trying to time your visit to the event, book months in advance. Rates from $20 (1-865-430-5560; recreation.gov).
