It's enormously easy to imagine a version of the 2007 killer crocodile movie Black Water that's considerably worse. That's because it would basically be the 2003 killer shark movie Open Water, a much-hyped movie that wasn't particularly good, but did create a model for ultra-low-budget thrillers set in one location with just a couple of actors playing characters fighting for survival in adverse conditions. It has proven to be a durable genre, undoubtedly because these films can be made for hardly any money, with variations including people trapped on a ski lift, in a coffin, in space, in an elevator, in a canyon, on a boat, on a boat, with sharks, and with sharks.

Black Water came early in this cycle of single-location thrillers, and like Open Water, it purports to be based on a true story, as it tells us in an opening card. It also tells us in an opening card that the population of both humans and saltwater crocodiles in Northern Australia has been steadily increasing, which doesn't actually do anything for us other than get "saltwater crocodiles" read into the record as soon as possible. It's certainly not the case that the encounter between man and crocodilian happens as a result of two species competing for space; the human crocodile fodder has to go quite out of its way to end up in a position to be eaten. That fodder consists of a small family road trip: sisters Grace (Diana Glenn) and Lee (Maeve Dermody) are going on a two-week vacation, along with Grace's husband Adam (Andy Rodoreda). The opening scene finds Grace and Adam picking Lee up and saying good-bye  to the women's pleasant mother (Fiona Press), in a scene obviously meant to increase the pathos when at least one of these people ends up in a digestive tract.

This is, I would say, the primary sin of Black Water, one on display over and over again in the film's opening 20 minutes. David Nerlich and Andrew Traucki, the film's writer-directors (who have not gone on to work as a duo; Traucki has kept directing, Nerlich has not) have given us a very mechanically precise first act of exposition: the scene with the mom, then a scene at a croc zoo where we see footage that shows us how the animals move (very fast, and straight up out of the water), how they can be baited, and provides a bit of information about the species. Then the three tourists head off to take a boat trip into the swamps, only to find that they've just missed the main tour guide, Barry. But the person who tells them this, Jim (Ben Oxenbould), is willing to take them, the implication that this is a little bit irregular and a little bit off the books.

This is all very clearly laid out, so clear that it feels less like we're watching events unfold than that we're seeing a clock being wound. Everything that happens in this opening stretch of the movie is there to solve a future storytelling problem or establish a very narrow and specific situation (that these people aren't supposed to be where they are and nobody will notice they're missing), and the filmmakers have gone to no lengths whatsoever to disguise this fact. Perhaps if one did not know that the point of the film was to watch these four people tangle with a croc, it wouldn't be completely obvious how mechanically the script is setting up events to pay off later. But the ominous opening card would seem to make sure that we would figure that out.

This all culminates in the inevitable first crocodile attack, as the four travelers arrive in a secluded lagoon of opaque muddy water and no clear sight lines in any direction. And like, I do mean that it happens as they arrive. Or close enough to it. The film is only 90 minutes long, so it doesn't have a huge surplus of running time, but it still gets to the first attack with what I would consider to be undue haste; this is maybe exacerbated by how grimly functional the writing has been up to this point, running a series of operations rather than letting the story breathe and letting us get a feel for who the characters are when they're not being put through the paces of a screenplay. As result, when the crocodile shows up, the film has no atmosphere, no sense of bucolic nature hiding grisly death; it just has a list of checked boxes.

Fortunately, as soon as the first victim vanishes into the murk (which is, of course, Jim), Black Water takes a sizable step up. Indeed, much to my surprise after the listless opening, this turns into quite a fraught horror-thriller, with the directors now revealing a gift for implication and menacing stillness that the opening act very strongly implied they didn't have. The immediate post-attack situation finds Lee trapped under (and then atop) the overturned boat, with Grace and Adam up a tree; the film at this point becomes a series of puzzles, both as to what should be done, and how it is to be done. The tension is generated simply enough: the camera is trained at the surface of the water, where every ripple  an every "blorp" on the soundtrack is invested with a horrible sense of mystery. Nerlick and Traucki have learned the right lessons from Jaws, and according don't let us see the crocodile at all for a very long time; even the attack that takes Jim is staged so obliquely that we're only slightly more sure than the characters are what happened to him. The result is that we're never given a clear instruction in what a crocodile attack looks like, in this film's visual language, so the whole movie is spent guessing: is this a sign of the croc? Is that a sign of the croc?

Black Water is thus able to extract quite a bit of genuinely draining tension out of very little actual material: people on the same tree, looking at the same crap floating in the same water. The three remaining actors are excellent at playing panic (especially Rodoreda, who does a very good job at playing Adam's "I'd rather try this and die than not try this and die" resolve as fundamentally terrified with a veneer of resolve, rather than just playing the resolve), and this panic is our only cue for what we should be feeling, so it ends up infecting the movie in exactly the right way.

The other impressive thing that the film does is to get at the sheer nightmare horror of this situation, particularly as night begins to fall. Without spoiling things too much, I will say that the croc's second victim is placed into a couple of tableaux that go pretty far afield from the rough and ready naturalism of the film up to that point, including a shot where the croc slowly emerges from the water with a body languidly drifting in the water on either side of its mouth; it's slow and solemn enough to have a kind of poetry to it, while being such a shocking note in a film that has neither really shown us much of the crocodile nor had anything of poetry in it that it feels like a hallucination. And this is not the only time that the body in question is placed in the center of a shot where the film's heavily realistic aesthetic takes on a certain baroque quality. By the time it's fully dark and raining, the images fully embrace this kind of strange expressive realism, and the actors' performance has modulated from panic into despair, to go along with it.

In short, once Black Water gets going, it's pretty good at marshaling its meager resources to create a small little portrait of terror, hopelessness and dread that feels more authentic in every way than the crass Open Water, for starters. That first act is still a huge liability, and the focus on intensifying the tension comes at the expense of the characters (the film tries to take some trite shortcuts to give the characters depth; it doesn't work), which makes it more of a successful exercise than something truly visceral. It is, after director Greg McLean's Rogue, the second-best Australian film from 2007 about people trapped in a lagoon with a saltwater crocodile, out of two. Still, as the kind of tightly focused movie that does one thing, it at least does it very well, once it decides to start. This is an admirable piece of genre filmmaking on a tight budget, exactly the thing that single-location survival thrillers are meant for, and there aren't very many films of this type that showcase that particular strength of the subgenre more elegantly.

Body Count: 3, a number that's much larger than it sounds given that the film only has five characters.