Ordered by the number of ascents recorded.
| Climb Name | Type | Grade | # Ascents Recorded | Notes | Exclude Reason |
|---|---|---|---|---|---|
| One 'ard Move | Trad climb | E6 | 1 | ||
| One for the Road | Boulder problem | 8A+ | 1 | ||
| One Inch Punch | Trad climb | E9 | 1 | ||
| One in the Swarm | Trad climb | E8 | 1 | ||
| One Man and His Dogmas | Trad climb | E5 | 1 | ||
| One Punch | Sport route | 9a+ | 1 | ||
| One Redeeming Feature | Boulder problem | 7C+ | 1 | ||
| One Step Beyond | Boulder problem | 8A+ | 1 | ||
| One Step Beyond | Trad climb | E6 | 1 | ||
| Onigoroshi | Sport route | 7c+ | 1 | ||
| Only Human | Trad climb | E5 | 1 | ||
| On The Beach | Boulder problem | 8B | 1 | ||
| Opal | Sport route | 8b+ | 1 | ||
| Opening gambit | Trad climb | HVS | 1 |
One of the first routes on slate, up the huge tottering back wall of Twll Mawr, the climb has been substantially altered by rockfall since Joe Brown’s first ascent and is now graded XS. An adventure strictly for connoisseurs. |
|
| Open Your Eyes | Sport route | 8c | 1 | ||
| Open Your Mind Direct R2 | Sport route | 9a+ | 1 | ||
| Ophir Broke | Trad climb | E5 | 1 | ||
| Optimus Prime | Boulder problem | 8B+ | 1 | ||
| Orange Crush | Trad climb | E6 | 1 | ||
| Orange Mécanique | Sport route | 8a | 1 |