According to the uploader, this chilling video was filmed using two GoPro cameras mounted onboard the Pocahontas, aka The Danny, as it was scuttled in Lake Worth, Florida in February 2013. The vessel now rests in 75 feet of water near Singer Island. The video was reportedly shot by Dean Shuler of Pura Vida Divers.
I hope that none of you will ever witness anything like this first hand, because this is terrifying. So stay safe out there.