I thought it was functional rather than gripping, although there were one of two moments where I was on edge. Ron Howard of 25- 30 years ago would have wrung more tension out of it.

I can appreciate the impulse to elevate the Thai contribution, ie diverting the rain waters, blocking the sink holes, etc, but I felt this was bolted onto the story in a rather perfunctory way. I don't think Howard was really interested in this sub plot, it seemed done as a gesture of cultural sensitivity.

The writing was bland - Farrell and Mortensen didn't have much to work with, their banter was forced, as were their accents. The divers in real life are no doubt very no-nonsense men, not prone to sentiment, but the story needed to coax put their personalities more, their motivations...not doing so lessened the impact of their triumph.

Gotta say, however, that Joel Edgerton was superb - one of the most natural actors working today.