This 11 January 2019 video says about itself:
Diving in the dark: exploring underground realms | Natural History Museum
Our drive to understand the evolutionary history of life on Earth leads us to search for clues deep underground. Cave divers are at the forefront of this research, helping us access some of the deepest and darkest subterranean and water-filled parts of our planet.
Discover some of the animals that prefer to live in the shadows here.