Petroglyphs and a waterfall among the many treasures you’ll discover on the short, easy hike to Keyhole Sink near Flagstaff

Who says you need to endure a long, strenuous hike to see cool stuff in Arizona? On the short, easy hike to Keyhole Sink Trail, located a half-hour west of Flagstaff, AZ, you can see petroglyphs, a waterfall, and much more.

Keyhole Sink interpretive sign with trees and rock wall in background

Quick take

Breathe in the scent of towering pine trees and enjoy the high-altitude breeze as you wind your way through the intermittent shade. In less than a mile, you’ll arrive at a picturesque lava flow sinkhole where you can discover petroglyphs etched into the rock by native people a thousand years ago.

If you time your visit just right, you might also see a waterfall refilling the sinkhole basin that some native tribes attach a spiritual connection to. Along the way, be on the lookout for massive tree stumps, ancient artifacts, tree frogs and other wildlife.

Why is it called Keyhole Sink?

Keyhole Sink is a rare oasis in the Kaibab National Forest. It’s a keyhole-shaped lava flow with a pool of water at its base known for seasonal waterfalls. A sink, short for sinkhole, is a topographic depression formed when underlying limestone bedrock is dissolved by groundwater.

rock wall and pine trees
When full, the sinkhole basin can hold around 60,000 gallons of water; roughly six times the volume of an average in-ground residential swimming pool

Hike summary:

  • Length: 3/4-mile one way, 1.5 miles round trip
  • Difficulty: Easy
  • Highlights: Petroglyphs, Waterfall (seasonal)
  • Precautions: Rugged shoes recommended
  • Trailhead: Oak Hill Snowplay Area
  • Pass/permit required: None
Note: 1 mile = 1.6 kilometers

As you hike to Keyhole Sink, keep an eye out for evidence of some of the area’s first residents in the ancient basalt lava rock. The region is the ancestral homeland to the native tribes including the Navaho, Hopi, Hualapai, Zuni, Havasupai, and Yavapai.

petroglyphs at Keyhole Sink
Discover petroglyphs at Keyhole Sink

What you’ll experience on this hike:

  • Tall, healthy stands of 100-year-old ponderosa pine trees and new-growth aspen trees
  • Ancient tree stumps left behind by lumberjacks who cut down trees in the early 1900s for a logging railroad
  • Petroglyphs etched into the rock wall at the end of the trail
  • A seasonal waterfall fed by snowmelt and rainfall

Hint: To view the petroglyphs, walk around the left side of the water basin.


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Some of the coolest things to see in Arizona require a lot of effort. Keyhole Sink does not. It’s a unique site with petroglyphs and a seasonal waterfall that’s fairly easy to get to. Just park in the Oak Hill Snow Play area lot (mapped below) and look for the trailhead gate across the road.

Before you go

Find out more about Keyhole Sink and download the interpretive hiking brochure.

How to get to Keyhole Sink

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