Shuttle buses are aimed at wildlife watchers and day hikers. They aren't fancy, comfortable, high-tech wonders but big, clunky school-bus-style affairs. On board, passengers armed with binoculars and cameras scour the terrain for animals, most of which are so accustomed to the rambling buses that they rarely run and hide. When someone spots something and yells 'stop!' the driver pulls over for viewing and picture taking.

The drivers are concessionaire employees, not NPS naturalists, but they provide unofficial natural-history information en route. Some are better at this than others.

Day hikers don't need a backcountry permit and can get off shuttle buses anywhere along Park Rd. After hiking, produce your bus-ticket stub and flag down the next bus that comes along. (Due to space considerations, you might have to wait a bus or two during peak season.) Many park visitors hop on and off buses several times in one day.

Certain buses head into the park as early as 05:15; the last ones are back by around 22:15. It's wise to reserve a seat as far in advance as possible. The cost varies based on how far you're riding, there's also a three-for-two pass, allowing three days of travel for the price of two.