Warning: I’m going to spoiler not only Sanctum (2011) but also The Descent (UK version only!) so that’s two spoilers for the price of one. I know, I spoil you.
Sanctum isn’t top notch claustrophobic caving (probably partly because we weren’t watching it in the original 3D). Though it often looks beautiful, and it’s quite fun, as indeed it should be – it was produced by James Cameron who knows a thing or two about water, and having a key character die just before the end.
To be fair nearly everyone dies in Sanctum though it’s a pretty big team to start with. It’s like watching the last night of Big Brother when they have to get down from ten to one in 90 minutes.

Unfortunately we never get to know anyone deeply enough to care if they do die, and despite it coming out in 2011 it suffered in our eyes as the film club watched it just a few weeks after 47 Meters Down: Uncaged (2019), which has a water-filled caving system AND an ancient Mayan temple AND blind killer sharks.
Sanctum only has the caves, rapidly filling with water after the divers accidentally start their exploration of the uncharted system just as a typhoon hits above ground.
There’s no external predator: just water above and below, the freezing cold, dead ends, and bad luck multiplied by their own stupidity.

Forced to explore further into the rocks in order to find a new way out, Sanctum‘s increasingly depleted group wriggle through tiny spaces into spectacular cathedral-like caverns.
Frank (Richard Roxburgh) is leading the expedition to map out the system, funded by Carl (Ioan Gruffudd), who has brought along his girlfriend Vic (Alice Parkinson).
Judes (Allison Cratchley) is experienced but very tired; St Jude was the patron saint of lost causes, which should tell you everything you need to know about Sanctum, and who dies first.
Also on the team is 17 year old Josh (Rhys Wakefield), Frank’s climber son, and yes they have ishoos, all the better to fill in the talky bits between the swimathons between caverns as they search for a way out (when Frank isn’t quoting Samuel Taylor Coleridge).
Every actor in Sanctum looks like someone more recognisable. Roxburgh could be a wet-suited Bryan Brown (a formative crush of mine since The Thorn Birds. Look him up!)
Gruffud is the poor man’s Dominic West. I suppose as their careers wax and wane the tables could turn and West might devolve into an Aldi Ioan Gruffudd, though as Liz and I are currently gripped by the continuing romantic revelations about West and Lily James, he has the edge.

The first caving casualty is Judes, and despite the name there’s only one of her. Diving ahead with Frank, she damages her air supply – his attempt to save her with “buddy breaths”, using his own mask between the two of them, fails when she panics and drowns.
She’s the first death but not the last. Like that initial loo trip on a wine-fuelled night out – after holding on as long as possible because once you go you’ll need it every five minutes – now Judes is deads, it’s open season. Most are drownings and mercy killings though there’s also an intriguing accidental self-scalping.
The ending is particularly moving, as Josh floats on an old door and Frank tries to cling on in the freezing water while telling Josh he loves him. I’m kidding.

Carl goes AWOL until near the end, when, sent mad by his girlfriend’s death and determined to wreak revenge, he comes across Frank and Josh. While Josh manages to overpower him, poor Frank lands on his back on a stalagmite.
And in case you get them confused – pointy rocks formed from calcium carbonate, not Frank and Josh – stalagmites stick up from the floor, and stalactites down from the ceiling. It’s easy to remember which is which because tights hang down, usually six inches below crotch level, let’s face it. (Obviously none of this is any use if you’re American and call tights “hose”, which is what we use to water the garden. Truly we are two great nations divided by a common language and your inability to make decent chocolate.)
Frank’s injuries are so bad he begs Josh to help him die, leaving his son to make his way out of the caves with one small tank of air left. He discovers Carl’s body on the way out, and just as he thinks his own journey will end without escape he sees Frank again, willing him on.
Spotting an opening out into the ocean, Josh surfaces outside, before crawling onto the nearby beach where there are people who can help him.

The film is based on true events, though most of it must be made up as in the real-life disaster no one actually died.
I’m assuming the most batshit scene in the movie is also fiction, though who knows? Now down to only Frank and Josh, they discover – via a trail of actual shit excreted by bats – a cavern open to the skies, with a WW2 Japanese tank sitting in the middle, which fell in during the war(!)
Josh is, presumably, the only survivor, though maybe Liz and JD made it out too. A pair of forgettable characters who were nearly at the surface when the typhoon sent a torrent of water gushing into the caves, we never find out what happen to them. Schrodinger’s Cavers, both dead and alive at the same time, they now exist in a bleak movie netherworld. I like to think that nearly at the top, they turned a corner and found Sarah from The Descent, having a birthday party with her imagined daughter while awaiting death-by-blind-subterranean-humanoids.
The Good-Bad Film Club rating
Sanctum is Good-Bad but not Ugly.
Post-movie search: Kubla Khan by Samuel Taylor Coleridge, and Xanadu by Olivia Newton John.
Post-movie info: Sad to discover that the diving expert and stuntwoman Agnes Milowka, who doubled the actress playing Judes in her drowning scene, herself died a few months later while caving in the same system.
We watched Sanctum on Netflix. It is also available on digital and physical media:
Check out the trailer now: