On the other hand, people who don't know diving terminology could find the lingo difficult to understand. Most used terms are not explained and neither are many of the reasons why cave diving in those depths is so dangerous. Maybe the English subtitles are easier to understand if diving slang is not used. Can't tell because I haven't seen those.
This is not a very detailed analysis of the events, but more a story about friendship and the psychological effects of the accident on the fellow divers.
The dead bodies can be seen briefly, but there are no close-ups which would make the footage graphic. In my opinion the most graphic parts of the documentary are the discussions held when planning for the recovery dive. What is the condition of the bodies, what equipment should be recovered etc.