Over the six hour live stream - and via at least four separate cameras - viewers were shown around the set, watched live interviews with everyone from director Andrew Traucki, the cast and crew, and were able to submit their own questions via a live comment feed.
There was also some pre-recorded footage and interviews from the ocean-based shoots earlier this month, and a good deal of shark footage - which Traucki shot off the coast of Australia earlier this year.
Even more incredibly, the RED camera The Reef is being shot on was hooked up to the live feed - so that viewers at home could watch (via a second camera) a scene being set up, with props, lighting, cast and all the on set banter between crew before cutting to the RED feed and watching the scene from the director and cinematographer's vantage point.
It's hard to describe just how incredible and immersive the experience was, but I haven't felt this buzzed about what I was seeing from a film set since Peter Jackson started his landmark series of video production diaries from the set of King Kong in 2005.
It was akin to watching DVD extras live, and the constant interaction between the people in front of the cameras and the audience gave the feeling we were on set with the cast and crew.
For anyone who missed it, selected footage will be online in coming weeks at http://www.reefmovie.com/