As long as you’ve got! You will need at least 3 full days just to get around all of the main sights and if you want to spend any time at them, 5 days. We have spent most of two consecutive weeks there before and still ran out of time to do all the things we wanted to do.

When you are planning your trip, take a look at the map on the Park Service website

http://www.nps.gov/features/yell/interactivemap/index.htm

You have to get out of your car to see this

To help with some idea of distances, the Grand Loop Road that takes you to the main attractions in the Park on a figure of eight is around 140 miles. When you are looking at distances however, understand you will be driving slowly. Yellowstone National Park has strictly enforced speed limits to protect both humans and animals, there are often road works – the roads are subject to very harsh conditions and require a lot of maintenance – and you will end up stopping to look at animals. There are frequently vehicles pulled over at the side of the road and it is worth stopping as you never know what someone may have spotted.

There are also times when things slow down as one of the Park’s animal inhabitants decides to use the road. We have ended up in several extremely slow moving queues of traffic, especially near Hayden Valley where the bison often use the road for their evening constitutional. Watching a bison striding toward you leading a parade of cars creeping along deferentially behind him is a lovely sight. It definitely beats being stuck on the M25 but don’t plan on whizzing from place to place.