Green to Black: Five Aerial Courses at Flagstaff's Fort Tuthill
An adult treetop obstacle park inside a county park, built as five color-coded circuits that climb higher and get harder as you go. Admission covers one rotation through all of them, and you can come down at any exit point along the way.
Flagstaff Extreme strings five circuits between the trees at Historic Fort Tuthill County Park. The operator describes each circuit as a mixture of roughly 10 to 17 obstacles, bridges, swings and ziplines, color coded by how high and how hard it gets: green, silver, blue, red, then black.
You start on the ground. A 30 minute training session covers the equipment and a demonstration course, then the green circuit lets you get used to clipping in before the ground drops away.
Admission covers one loop through the adult courses, and at any exit point along them you can descend and walk back to guest services.
There is one booking option. The booking allows one to fifteen travelers. Taxes, fees and handling are included. Food, drinks and getting yourself to the park are not.
Flagstaff Extreme Adventure Course-Adult CourseAges 12 and up, 3 to 4 hours, at Historic Fort Tuthill County Park. One rotation through five color-coded circuits of obstacles and ziplines. All taxes, fees and handling charges included.www.viator.comGreen, Silver, Blue, Red, Then Black
The circuits are meant to be done in order, each one higher and harder than the last. The operator puts check-in, the safety briefing, the demonstration course and all of the adult circuits at roughly three hours; the booking lists three to four.
Finishing all five is not the default outcome. Across the full pool of 145 traveler reviews for this course, the black circuit is the one people name as the wall. One traveler wrote in 2021 that three of their party of five completed black, one of them barely and with assistance. Another, writing in 2023, described a pair of 15 year olds stopping about three quarters of the way round while the grandfather finished in two hours.
That is the design working as intended. The exits are there because stopping partway is expected.
The operator also reserves the right to close parts of the course for maintenance, updating or staff training, and says guests may repeat a section to make up for anything unavailable. Admission covers five circuits. Whether all five are open on the day you go is a separate question.
Your Hands Give Out Before Your Nerve Does
The thing most likely to end your day is grip. You are holding steel cable for hours, and fourteen reviews in the pool raise gloves specifically.
The operator recommends fingerless gloves and sells them at its welcome center. One traveler writing in 2026 described going bare handed and picking up some pretty tough blisters, and recommended leather gloves. Another, writing in 2025, noted they are sold at check-in at a good price. Gloves are not included, so plan to buy them separately at check-in if you need them.
Height matters less than people expect. Several reviewers who describe a fear of heights still finished the course. The word that keeps coming back about the later circuits is fatigue. Water helps more than courage does.
One Measurement Decides Whether You Can Ride
There is a reach requirement, and it is a hard gate. The operator states that to reach the safety lines and work through the adult course, a guest must be able to reach the middle of their palms to a height of 5 feet 11 inches, which is 180 centimeters, while keeping their feet flat on the ground.
The operator's own FAQ puts its weight limit at 275 pounds. The booking page carries the same passage with the example at 285 and stops before the ceiling, so treat 275 as the figure that counts. Fit matters as much as the number: the operator's example is two people at the same weight, a 6 foot 5 one the harness takes and a 5 foot 2 one it probably will not.
The adult course starts at age 12, and the operator says a tall 11 year old who can reach still does not qualify. Anyone aged 12 to 15 needs an adult who climbs with them at one adult to three teenagers, staying within two platforms. Watching from the ground does not count, and if the adult stops the teenager comes down too. Every participant fills out a waiver. The booking asks for at least a moderate level of physical fitness, and reviewers consistently back that up: good balance and grip strength, sore arms the next day.
It Runs in the Snow, and That Cuts Both Ways
Flagstaff Extreme operates rain or snow or shine. A traveler writing in April 2024 described arriving after six inches of snow overnight and being glad to find it open.
Only severe conditions close the courses: lightning within about six miles, winds over 40 miles per hour, fire conditions, extreme cold, and possibly heavy rain or snow. In December, January and February the operator puts that cold line at 25 degrees Fahrenheit and runs when it is above.
If the park does close and you have waited more than an hour, compensation depends on how many circuits you have completed. Guests who have completed two circuits or fewer can receive a rain check or a refund. Guests already on the third circuit or beyond are issued a rain check, which is valid for 60 days from issue or the current season year, whichever comes first. A traveler writing in August 2026 described being stopped on their final circuit, asking for a voucher, and being turned down, and read the one hour rule as the reason. Worth knowing before you are standing at the bottom of a tree in the weather.
Dress for it. No open-toed shoes, no flip-flops, no slip-on shoes, no loose or baggy clothing and nothing tied around your waist. Long hair tied back, eyeglasses secured, and the operator strongly recommends leaving necklaces and loose bracelets behind, since they can catch in the equipment. Wear something you do not mind picking up dirt and sap, because these are trees.
Anyone who comes along without climbing does not need a ticket. The course sits in a county park, so they can walk the trails and watch from the ground for nothing. The rules are that nobody gets up on any part of the course, and nobody stands directly underneath it.
The ground around the course is wheelchair and stroller accessible. The course itself is very physical. Service animals are allowed.
Two travelers five years apart describe paying for a staff member to go round with a nervous first-timer. That is not one of the options on this booking.
Pace yourself on silver and blue, keep something in reserve, and the black circuit is still there at the end of the afternoon waiting to find out whether you meant it.