Silence (also Project Hard), is a 45-metre (148 ft) severely overhanging sport climbing route in the granite Hanshelleren Cave in Flatanger Municipality, Norway.

To complete the route, Ondra undertook specialist physical and mental training to overcome its severely overhanging terrain.

[2] Ondra bolted the route in 2012–2013 – while he climbed Change [fr] 9b+ (5.15c) at Flatanger, the world's first 9b+ – but dropped the project for a period saying: "I could sort of imagine doing the individual moves, but I could see that linking the whole sequence, with its 8C boulder, all the way from the ground just looked way too ridiculous".

[3] After retrying it in 2015 and working through some of the technical challenges,[3] Ondra began to commit more time to the project calling it "my lifetime goal", in a 2016 interview with Climbing.

[11][6] Ondra described it as "much harder than anything else" he had previously done, and cautiously suggested the 9c (5.15d) rating, telling The Guardian, "Everyone knows what it means to run 100-meters in a world record time.

[14][15] In April 2022, French climber Sébastien Bouin – a frequent climbing partner of Ondra – established the world's second-ever 9c (5.15d) route, which he called DNA [de], in the La Ramirole cave, Verdon Gorge in France; it also remains unrepeated (2023).

[8] Ondra estimated that the first 20 metres (66 ft) is at about 8b (5.13d) with good kneebar rests,[7] and similar to the beginning of neighbouring routes Nordic Flower, and Change.