Are you afraid of heights? Do you cringe at thought of tight spaces? Do you hate getting dirty or can’t tolerate extreme temperatures? If so, you can skip this article. (Or, if you’re curious, read 5 Tips to Survive an Obstacle Course Race.)

But if you are looking for something unique that will challenge you physically and mentally, a Tough Mudder competition may be just what you need. (Start training with STACK’s Training for Mud Runs, Part 1: Schedule Overview.)

Founded in 2010 by Will Dean and Guy Livingstone, the Tough Mudder consists of a 10- to 12-mile obstacle course designed by British Special Forces to test the strength, stamina and mental grit of their recruits.

Although you can enter a Tough Mudder competition on your own, the organizers encourage teamwork, and many obstacles are intentionally designed to be difficult to complete alone.

How do you know if you’re ready to join a Tough Mudder team or take on this extreme challenge on your own? First, you need to be in the best shape of your life. But it’s also important to know exactly what you will be getting into. (Check out 3 Unconventional Obstacle Race Training Drills.) So here’s a list of some of the really fun obstacles you could encounter if you choose to push yourself to the limit in one of these events.

Arctic Enema

Participants jump into icy water, swim through the ice under a wooden plank and pull themselves out on the other end before they become hypothermic.

Bale Bonds

Tough Mudders hurl themselves over (or through) a stack of hay bales—while watching out for the pitchfork inside.

Berlin Walls

Participants must scale three 12-foot wooden walls strategically placed where they are at their weakest during the event. While some Tough Mudder participants manage to pull themselves over the walls on their own, this obstacle was designed with teamwork in mind. Most participants need a boost from their teammates to conquer this one.

Boa Constrictor

Participants have to crawl through a series of pipes that force them downhill into some freezing mud, then navigate a slippery uphill climb to the other side.

Cliffhanger

To complete this obstacle, Tough Mudder participants must scale a 40-foot cliff of slippery mud angled at 45 degrees without sliding back into a muddy pit below.

Devil’s Beard

Tough Mudders must pass underneath a cargo net fastened low to the ground, which is sometimes placed on an uphill slope.

Dirty Ballerina

Participants must jump over 5-foot wide mud pits without falling in.

Electric Eel

Tough Mudder participants must slide on their bellies through freezing water, avoiding the live wires above them.

Electroshock Therapy

Participants must sprint through a field of live wires—some carrying as much as 10,000 volts of electric shock—while watching out for hay bales and deep mud.

Everest

Participants must sprint up a mud and grease-coated quarter-pipe without slipping back to where they started.

Fire Walker

Participants run through pits of blazing firewood with flames at least four feet tall, then leap over the final pit of fire into a pit of ice-cold water.

Funky Monkey

This obstacle puts a new twist on the monkey bars; some bars have been greased with mud and butter, and participants must tackle them at an incline for the first half, then descend down for the second half without falling into the icy pond below.

Greased Lightning

Tough Mudder entrants must slide down a slippery slope (sometimes set up on a snowy mountainside) into a muddy pool of water at the bottom.

Hangin‘ Tough

Similar to Funky Monkey, participants swing eight feet above cold water, grabbing greased rings.

Hold Your Wood

Participants must carry a heavy log through a section of the course (over a half mile on flat terrain, or uphill).

Kiss of Dirt

Mudders must belly-crawl through mud under barbed wire set 8 inches above the ground.

Mud Mile

Participants have to slog through up to a mile of waist-deep sludge and try not to lose their shoes in the mud.

Spider’s Web

Tough Mudder entrants must crawl like a spider up and over a cargo net suspended between two trees without falling into the net below.

Trench Warfare

Participants crawl through narrow, dark, muddy trenches filled with rocks and other obstructions.

Twinkle Toes

Participants must maintain their balance to cross a narrow wooden beam without falling into the icy pond below.

Underwater Tunnels

Tough Mudder entrants swim through ice-cold water while bobbing underneath rows of floating barrels.

Walk the Plank

Participants jump from a 15-foot-high plank into freezing water below while getting verbally chewed out by Marines at the top.

If the description of the obstacles above excites you rather than scares you, be prepared to train for 12 to 16 weeks for the event. Visit http://toughmudder.com/events/ to find future Tough Mudder events near you.