Yellowstone in 4 days

Not the tallest geyser but the most predictable, erupting roughly every 90 minutes, with boardwalks leading on through the Upper Geyser Basin.

America's largest hot spring, over 100 metres across, deep blue in the centre and ringed with orange, yellow and green bacterial mats.

North America's largest high-altitude lake, with the West Thumb Geyser Basin on its shore, where hot springs bubble at and below the waterline.

Wet meadows along the Yellowstone River between the lake and the canyon, with bison herds that block the road, plus coyotes, pelicans and trumpeter swans.

A 32 km gorge cut into yellow and pink rhyolite, with the 33-metre Upper Falls and the 94-metre Lower Falls, twice the height of Niagara.

The hottest and most acidic basin in the park, home to Steamboat, the world's tallest active geyser, whose major eruptions come days or years apart.

Near the north entrance, hot water lays down travertine as white and ochre terraces that change from year to year, along boardwalks from Liberty Cap.

Nicknamed America's Serengeti, the best place for large animals: bison herds, elk, pronghorn, and the wolves reintroduced in 1995, watched every morning through scopes.