Dorothea Quarry - trimix diving the 57m tunnel 21.5.22 

A full video of the swim through of the 57m tunnel at Dorothea Quarry, N Wales. UK. Diving done on AP XPD units running hypoxic trimix. Scuba diving and Rebreather diving interest. BSAC technically qualified divers Mike Smith and Terry Simpson.
Learn to tech dive before attempting this. Diving to these depths on air is extremely dangerous. To dive Dorothea you now need to join BSAC and also North Wales Technical Divers BSAC club. You need to prove technical qualification and be well versed in deco diving. The site goes to 108m and has no facilities. It is basically wild diving.