It's geyser day! First stop was Porcelain Basin in the Norris Geyser Basin. Porcelain was home to several small geysers, hot springs and fumaroles.

Emerald Spring was a gorgeous site along the trail to the Back Basin at Norris.

"Pewwwwww! This smells like rotten eggs!"

The cows hold their noses as sulfurous steam rises from a fumarole at Norris.

Vixen Geyser was a delight as it sent spurts of water into the air.

Moving on to Yellowstone's Upper Geyser Basin, Lunch and Snack arrive at the venerable Old Faithful Inn. Built in 1904, it is one of the few log hotels still standing in the United States and was the first of the great park lodges.

"This is astounding! Look how high the ceiling is!"

The inn's huge lobby was an amazing sight for Lunch and Snack.

"There it is! Old Faithful!"

The world-famous geyser was one of the first in the park to receive a name, reflecting on the predictability of its eruptions.

The average height of an eruption is 145 feet but it can spout up to 180 feet on some occasions.

Lunch and Snack celebrate seeing the geyser with a beer in a nearby restaurant in Old Faithful Village. Even though it was served in a Yellowstone-branded cup, the beer itself, Centennial IPA by Flathead Lake Brewing, was brewed to celebrate the 100th anniversary of Glacier National Park in Montana.

"Well Snack, that's kind of a strange mix."

A stroll around the Upper Geyser Basin brought them to Grotto Geyser, one of the oddest of the cone geysers. It was gurgling like mad, but didn't erupt while the cows were there.

Morning Glory Pool was a riot of color as the sun began to set on the Upper Geyser Basin.

On their last day in Yellowstone, Lunch and Snack visit Clepsydra Geyser in the Lower Geyser Basin.

"This geyser was named for the Greek word for water clock because it erupts about every three minutes."

"Excellent timing, Snack."

Moving on to the Midway Geyser Basin, the cows marvel at Grand Prismatic Spring, the largest hot spring in the United States. It was named for its striking colors that match the colors of white light refracted through a prism.

"Gosh Lunch, I know its beautiful, but the colors are difficult to see through all the steam!"

The traveling bovines cross the Continental Divide as they head towards the southern end of Yellowstone. It was one of several crossings in the course of their journey.

Lunch and Snack take in the view of Yellowstone Lake from the West Thumb Geyser Basin. The area features a collection of hydrothermal features along the shoreline, but haze was beginning to obscure the view to the other side of the lake.

"I don't know if I like the looks of all the smoke hanging in the air."

Smoke from wildfires around the region was beginning to drift across the park.