Watch: An Ogof Ffynnon Ddu Through Trip

Climb a mountain underground with YouTube user OverNunderground during a through trip of Wales’ Ogof Ffynnon Ddu, the deepest cave in the UK.

According to the description, the group of four began at the bottom entrance and arrived at the top entrance just over 5 hours later. Fortunately the video has been limited to just the highlights.

[via ukCaving.com]