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The 7 Hardest Boulder Problems in the World (2024 Guide)

Aidan Roberts projecting the hardest boulder problem in the world

Published on: 07/20/2023

By Owen Clarke


Bouldering is a form of free climbing. It is one of rock climbing’s most simplistic (and difficult) disciplines. Boulderers ascend short sections of rock, typically freestanding boulders, sometimes up to 20 feet. Boulderers climb without any protection, save except for a pad (or pads) placed below the route, also called a “problem.” In this article, we’ll learn about the seven hardest boulder problems in the world.


Before we dive into the hardest boulders, let’s talk bouldering grades. Boulder problems are often graded using different systems depending on where you’re climbing. In the United States, we use the Hueco system, also known as the V-Scale. Across the Atlantic, the French Fontainebleau (or “Font”) system is dominant.

Other bouldering grading systems include the Dankyu Scale (Japan) and the UK technical system, which is normally used for roped climbing but occasionally appears on boulder problems. Another scale is John Gill’s “B” system, conceived in the United States in the 1950s.

climber on a difficult boulder outdoors
Photo by Daniela Araya

The B system, which was the world’s original bouldering grading scale, has all but gone extinct today, largely due to its simplicity. (It only contains three categories, B1, B2, and B3, making it hard to delineate between the hardest boulders as the benchmark is continuously pushed.)

For clarity, in this article, I’ll describe climbs using the Hueco scale. We have a helpful grade conversation chart if you get confused, or would like to learn more about climbing grading systems.

Modern Bouldering Outside vs. Inside

Bouldering is practiced both outside, on rock, and inside, on plastic. The vast majority of the world’s hardest outdoor boulder problems are located in North America and Europe, with a few in Japan. This is perhaps not as much a factor of what is available as it is what has been developed. There remains stellar potential on all continents.

After the European nations and North America, South Africa’s Rocklands is perhaps the best destination for those searching for the hardest boulders, certainly in the Southern Hemisphere.

To learn more about outdoor bouldering and how to begin, check out our Outdoor Bouldering Beginners Guide.

Natalia Grossman at the bouldering championships
Natalia Grossman © ISFC

Inside, bouldering is an excellent entry point into climbing, as it requires no technical knowledge (like knots) or gear (like harnesses, ropes, carabiners, belay devices, and helmets). All you need to boulder is a pair of climbing shoes and a pad to land on, and all climbing gyms have padded floors already.

Bouldering is also one of the disciplines in competitive climbing, both in the IFSC and the Olympic Games.

Bouldering Rock

Any type of rock that accommodates roped climbing can also house bouldering problems. The five types you’ll find as a climber are sedimentary (sandstone and limestone), metamorphic (quartzite), igneous plutonic (granite), igneous volcanic (basalts), and hydrothermal and metasomatic (quartz).

Now enough chatting about basics. Let’s talk about the world’s hardest boulder problems, starting with the legendary…

1. Burden of Dreams (V17): Lappnor, Finland

Nalle Hukkataival (FA, 2016), Will Bosi

The mighty Burden of Dreams was the first boulder in the world proposed at V17 when Finnish climber Nalle Hukkataival made the first ascent way back in 2016, and today it is the only V17 problem that has been confirmed by repetition.

Scottish climber Will Bosi made the second ascent in April 2023, agreeing with the grade. This makes it, for the time being, officially the hardest boulder problem in the world.

YouTube video
Will Bosi on the world’s hardest boulder

Although it is only 13 feet and eight moves, this 45-degree, crimp and crystal overhang is certainly one of the roughest sequences in our sport. Hukkataival developed the route and sent it over three years.

Along with several other top climbers, including Aidan Roberts, Bosi worked on the problem religiously in recent months. He spent 14 days on the red granite boulder, live streaming many of his sessions, and 10 days on a 3D-printed clone at Lattice Training’s headquarters in Sheffield, England.

Bosi ultimately sent the problem on April 12th, becoming the second climber to send a confirmed V17 9A.

2. Return of the Sleepwalker (V17 Proposed): Black Velvet Canyon, Nevada, USA

Daniel Woods (FA, 2021)

American mega-crusher Daniel Woods put up this sit start to Jimmy Webb’s Sleepwalker (V16) to much aplomb in April 2021.

The sandstone boulder problem, in Las Vegas, Nevada’s Black Velvet Canyon, was then only the second proposed V17, after Burden of Dreams. It is the hardest problem in America. Woods’ sit start added a seven-move V13 leading directly into Sleepwalker without a rest.

Woods had made the first repeat of Sleepwalker in 2019, just a month after Webb, and dove into the sit start in January of 2021. Ultimately, he spent a month alone working the route. For the final 20 days of projecting he camped near Return of the Sleepwalker, climbing the base line Sleepwalker 15 to 20 times (as many as four times in a single session) to dial the beta.

YouTube video
Daniel Woods on Return of the Sleepwalker

Return of the Sleepwalker has yet to allow a second ascensionist up its face, so it remains unconfirmed.

That said, Daniel Woods is one of the best boulderers in the world, and much older and more experienced than younger senders like Roberts, Bosi, and Shawn Raboutou. The 33-year-old was perhaps the leading pioneer in the development of both the V15 and V16 grades, and with that in mind, his grade proposal at V17 is arguably strong enough to stand on its own.

3. Megatron (V17 Proposed): Eldorado Canyon, Colorado, USA

Shawn Raboutou (FA, 2022)

Colorado’s legendary Eldorado Canyon State Park may be known for its hordes of stellar trad lines (and crusty trad dads), but it’s also home to one of only two proposed V17s in the United States.

Megatron, from American Shawn Raboutou, adds a seven-move V15 sit firing right into Daniel Woods’ Tron (V14) for a total of around 17 moves. When the young crusher took it down in 2022, after working on it in earnest since the fall of 2021, it become the United States’ second proposed V17, after Return of the Sleepwalker.

YouTube video

Like Return of the Sleepwalker, however, the sandstone Megatron has yet to see a repeat. Both Daniel Woods and Drew Ruana have spent a lot of time dialing in the moves (with Ruana logging a whopping 70+ days on the problem), but to date, it remains unrepeated and unconfirmed at V17.

4. Alphane (V17 Proposed): Chronico, Switzerland

Shawn Raboutou (FA, 2022), Aidan Roberts, Will Bosi, Simon Lorenzi

Shawn Raboutou’s Alphane in Chronico, Switzerland is currently the only other V17 proposal in the world, and thus Raboutou is the only climber to have potentially two V17 FAs. He made the first ascent of this granite problem on April 6, 2022, shortly before declaring his send of Megatron.

Raboutou battled Alphane‘s moves over 25 sessions, However, Alphane was on the radar of pioneer Dave Graham since the early 2000s, so it could be the first discovered V17 in our sport.

YouTube video

Alphane consists of a V14 start leading into a V15, followed by a V10 top-out. Raboutou and others who have completed or worked on the problem noted that the line’s difficulty wasn’t any individual move, but stylistic transitions one must move through to complete it.

The problem begins with power climbing on crimps, moving into open-hand positions with technical heel hooks and drop knees, and finally topping out under V10 pressure. Altogether, it takes the typical power-heavy boulder scene and adds a hefty focus on endurance.


Alpahane was repeated by Aidan Roberts in October of that year, Will Bosi in November, and Simon Lorezni in December. The former kept mum on his thoughts regarding the grade, and the latter indicated that he thought it was easier than Honey Badger (V16), while Lorenzi agreed with V17, but said that his other problem Soudain Seul (V16/17) felt harder than Alphane.

Will Bosi climbing a hard boulder in Switzerland
Will Bosi

With two climbers suggesting V17, one suggesting V16 at best, and a fourth not commenting, it’s hard to argue that Alphane is rock-solid at the V17 grade.

When you consider that Simon Lorenzi’s other V17 proposal (Soudain Seul, see below) has proven debatable at V17, and involved the use of a kneepad and book, it casts the projection into further doubt.

5. No Kpote Only (V15/16), Fontainebleau, France

Charles Albert, (FA, 2019), Ryohei Kameyama, Nico Pelorson, Illya Bakhmet-Smolenskyi

The Charles Albert boulder problem No Kpote Only, located in one of the birthplaces of the discipline (and the Font grading system), is no longer considered V17, but it’s a legendary, stiff problem that more than merits inclusion on a list of Earth’s hard boulders.

Local phenom “Barefoot Charles” Albert tackled this line (you guessed it) barefooted in January of 2019, after working on it beginning at the end of the previous year. The name translates to “No Shoes Only,” in honor of the way Albert worked this and all his routes. He suggested V17.

However, Japanese strongman Ryohei Kameyama snagged a repeat in March, suggesting a downgrade to V16/V17. In October 2020, fellow Frenchman Nico Pelorson took the third ascent, and the more climber took No Kpote Only down another notch, recommending V15.

Charles Albert on No Kpote Only, one of the hardest boulder problems in the world
Charles Albert

In May 2022, Ukrainian young gun Illya Bakhmet-Smolenskyi (who is only 17 years old) made the fourth ascent, declining to grade the route due to his inexperience. “I can’t say anything about the grade [be]cause [I’ve] never tried a proper [V15] before,” he said, “so I’ll just wait till the grade settles.”

No Kpote Only is almost certainly not a full-fledged V17 when wearing climbing shoes, but its real grade will only emerge after more climbers complete the line.

But regardless, it’s worth noting that not a single one of the repeat ascents was performed as Albert intended (no shoes only). If they had, maybe his V17 grade would have felt more real.

6. Soudain Seul / Big Island Assis (V16/17): Fontainebleau, France

Simon Lorenzi (FA, 2021), Nico Pelorson, Camille Coudert

Simon Lorenzi’s Soudain Seul (also known as Big Island Assis, or Big Island Sit) near Fontainebleau was proposed at V17 when he made the first ascent in February of 2021, making it only the second of the grade after Burden of Dreams.

Like No Kpote Only, this boulder problem is also in the legendary haven of Font. The climb moves up a rail into an existing V15 line (Big Island) put up by Vincent Pochon.

This beginning add-on follows the sloping rail, requiring body tension, delicate feet on small edges, and (famously) kneebars. In total, it bumps up Big Island to around 20 moves, with half a dozen burly V12 moves at the outset.

YouTube video

When Lorenzi made the FA, he notoriously slid a book (entitled Soudain Seul or Suddenly Alone in English) underneath his kneepad to widen the span of his kneebar, a move that many in the climbing community saw as poor form, if not downright aid.

In any case, Lorenzi suggested the grade of V17. However, when Nico Pelorson made the repeat a month later, in March (also using a book), he modified the suggested grade to V16. A third ascent, from Camille Coudert in February of 2022, saw the Frenchman agree with Lorenzi at V17. (Coudert also refrained from using a book, unlike the other two climbers).

As it sits, Soudain is definitely a remarkable accomplishment, and one of the most difficult climbs in the world, but we’ll need to see multiple repeats to know more.

7. Off the Wagon Sit (V16): Val Bavona, Switzerland

Shawn Raboutou (FA, 2018), Daniel Woods, Jimmy Webb, Giuliano Cameroni, Sergei Topishko, Yannick Flohé

Only a few years ago, V16 was a mythical grade, but today over 30 climbers have sent V16 problems, and there are more than 20 proposed V16s in the world. You can’t pick the “best boulderer” in the world (names like Drew Ruana, Fred Nicole, Adam Ondra, Jimmy Webb, Christian Core, Paul Robinson, Ryuichi Murai, Griffin Whiteside, James Squire, Matt Fultz, and many others would be added to those mentioned above).

In the same manner, when picking the next “hardest” boulder, particularly after the V17s, there is no clear contender.

V16s Hypnotized Minds, Box Therapy, and Creature from the Black Lagoon in Rocky Mountain National Park are all strong contenders, not to mention The Ice Knife SDS. Moonlight Sonata in Joe’s Valley and The Process in Bishop are two others. Some V15s, like Monkey Wedding, are also worth mentioning in any list of hard boulder problems.

YouTube video

A Bouldering Monument

However, I’d like to highlight Off the Wagon Sit (V16). It’s certainly not the hardest V16 out there, but it is fairly historic. Shawn Raboutou made the first ascent of this modified take on Nalle Hukkataival’s Off the Wagon (V14), in 2018, adding a sit start, which has since been repeated by some of the world’s top climbers, including Daniel Woods, Jimmy Webb, and Giuliano Cameroni.

Some, like Daniel Woods and Jimmy Webb, have used the route’s wagon for a true “sit” start, while others, like Sergei Topishko and Giuliano Cameroni, have moved the wagon and stand started from the ground, although the holds are the same.

In January 2022, Sergei Topishko attempted a sit start completely from the ground which would add two moves to the normal sit start on the wagon. He couldn’t send this link up, but it’s definitely the next step in Off the Wagon‘s progression.

Will this addition push it up into V17? Who knows…

Frequently Asked Questions

What’s the hardest indoor boulder problem?

Currently, the world’s hardest indoor boulder problem is likely the Burden of Dreams replica route (1) in Sheffield, England. This 3D-printed plastic problem was used by top-end boulderers like Aidan Roberts, Will Bosi, and Stefano Ghisolfi while training to send Burden of Dreams (V17). Bosi ultimately made the second ascent.

How many people have climbed V17?

V17 is still a very ephemeral grade, as half of the four proposed V17 problems in the world have seen only one ascent, and a third, Shawn Raboutou’s Alphane, seems a likely contender for a downgrade. However, if all four proposed V17 problems are truly V17, then six climbers have climbed V17: Raboutou, Nalle Hukkataival, Daniel Woods, Will Bosi, Simone Lorenzi, and Aidan Roberts.

What is a V17 boulder?

V17 (or 9A, on the Fontainebleau Scale) is the hardest grade for a boulder problem in the world. A V17 boulder is thus one of the world’s hardest bouldering routes. Currently, there are only four proposed V17 problems in the world.

Is Burden of Dreams really V17?

V17 remains a nebulous grade, given that there are only a few problems at that level and only a few climbers who have completed them. However, if any V17 is a V17 it’s Burden of Dreams. Today, Dreams is the only V17 in the world that has been repeated and confirmed at the grade. It is the world’s hardest boulder problem.

What’s the hardest boulder problem sent by a woman?

V15 Horizon in the region of Mount Hiei, Japan. Ashima Shiraishi climbed it in 2016 when she was only fourteen (2).


The Hardest Indoor Boulder Problem Ever Built
Lattice Training on YouTube

14 Year Old Achieves Hardest Boulder Climb Ever Done by a Woman
Andrew Bisharat (Mar, 2016)
National Geographic

Main photo: Aidan Roberts on Burden of Dreams, © Catalyst Climbing

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