Will Bosi has been with Lattice since the very beginning, joining the Lattice team in 2015 as an athlete, and is currently training on a Climbing Training Plan PLUS, written by coach Tom Randall.

A world class climber from Edinburgh, Scotland, Will began his climbing journey at the age of six when his father took him and his sister to a local indoor centre. Since then, Will has become one of the world’s most accomplished boulderers and sport climbers.

A former member of the GB team, Will shifted his focus to outdoor sport climbing and bouldering in 2021, starting an incredible run of hard climbing ticks.

In 2021, he made the first ascent of ‘King Capella’ (9b+/5.15c) in Spain, a line that firmly established him as one of the world’s elite climbers. That same year, he completed two standout ascents at Raven Tor in the UK, the first repeat of ‘Mutation’ (9a+/5.15a) and the first ascent of ‘Brandenburg Gate’ (9a+/5.15a). (ukclimbing.com)

In 2022, Will continued this momentum with the third ascent of ‘Alphane’ (V17/9A) in Switzerland.

In April 2023, he achieved the second ascent of ‘Burden of Dreams’ (V17/9A) in Finland, one of the hardest boulders in the world, originally established by Nalle Hukkataival. This iconic send came after 10 dedicated sessions and hours spent training on a 3D printed replica of the holds at Lattice HQ and 14 sessions on the Finnish boulder itself.

In February 2024, Will added yet another V17 to his list with the first repeat of ‘Return of the Sleepwalker’ (V17/9A) in Red Rocks, USA. A few months later, in July 2024, he turned his attention back to Scotland and made the first ascent of ‘Harambe’ (V14/8B+) at Dumbarton Rock, a powerful line featuring a challenging double gaston move in the roof. By October 2024, he had completed the second ascent of Aidan Roberts’ ‘Spots of Time’ (V17/9A) in the UK, becoming the first climber ever to send four boulders at the world’s hardest grade.

More recently, Will added major new benchmarks across both rock and bouldering. In February 2025, he made the second ascent of Stefano Ghisolfi’s ‘Excalibur’ (9b+) at Drena near Arco, Italy. (ukclimbing.com) In the same year, he established new hard boulders including ‘El Dorado Sit’ (8C) in Sintra, Portugal, and ‘Realm of Tor’ment’ (9A/V17) at Raven Tor. (ukclimbing.com) In January 2026, he started the year by establishing ‘Pôr do Sol’ (8C+) in Sintra, proposed as Portugal’s hardest boulder. (ukclimbing.com)

Will’s achievements also include flashing V14, sending multiple V15s, and establishing the Peak District’s hardest boulder problem, ‘Honey Badger’ (V16/8C+), in 2022. Beyond his impressive sends, Will is known for his meticulous preparation. His training often includes using portable tools like the MXEdge Lift to maintain his incredible finger strength on the go.

Follow Will Bosi on Instagram.

Listen to our podcast with Will, talking Burden of Dreams and replicas.