https://www.rd.com/list/ocean-mysteries/

The Mariana Trench

http://www.deepseachallenge.com/the-expedition/mariana-trench/

The Bloop

https://www.youtube.com/watch?v=ZA2wY5-yiGY

Closing  music:

Impending by Hayden Folker | https://soundcloud.com/hayden-folker Music promoted by https://www.free-stock-music.com Creative Commons Attribution 3.0 Unported License https://creativecommons.org/licenses/by/3.0/deed.en_US