Unlike many mystery sound cases which seem to rely only on witness recollection, a recent event in the UK was recorded by a man who managed to capture the noise using his cell phone.

Joao Caetano, who resides in the city of Plymouth, noticed the eerie sound while out walking with his wife and, thankfully, was astute enough to record the moment for all to hear.

In the video, a distinct and haunting wail almost reminiscent of an undersea creature's call can be heard amidst the ambient sounds of the city.

Check out the strange recording at the Coast to Coast AM website and see if you can identify what the sound might be.