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We learned that there are few things in the world that are more dangerous than a 25-foot-long great white shark in Steven Spielberg’s Jaws. Namely, aluminum SCUBA tanks.

Why someone would strap on a mini-bomb of such design to their backs is beyond me, but divers do it every day. Of course, they rarely spontaneously explode, most likely because there isn’t a small-town sheriff firing a rifle at them while they dive.

As Matt Hooper (Richard Dreyfuss) and Chief Brody (Roy Scheider) begin their mission aboard the Orca, one of Hooper’s SCUBA tanks falls over. Hooper immediately explains how dangerous this is and how the compressed air inside the tank could basically ignite the entire ship and wipe out life as we know it on planet earth. Okay, so he maybe doesn’t say those exact words, but the implication is clear: SCUBA tanks are hella dangerous and have the potential to explode.

Fast-forward 45 minutes, and we find out that Jaws has sent Hooper fleeing to the continental slope, snacked on Orca captain Quint (Robert Shaw), and left the Orca sinking in a slick of oil and chum. In a last-ditch effort to save the day, Chief Brody climbs to the tilting mast and starts firing a rifle at the charging shark. With one of the best final dispatching lines in movie history (“Smile, you sonofabitch!”), he shoots the SCUBA tank lodged in Jaws’ jaws, and the shark explodes like a trailer park meth lab.

So it got us wondering: can a shark be killed by shooting a SCUBA tank lodged in its mouth?

The Answer: Yes (but not exactly like we thought)

Spielberg hasn’t shied from the fact that the ending of the film might be utter hogwash. He made the change from the original novel (in which the shark dies from being harpooned multiple times by Quint) because he felt the scene was a downer, and the film needed a rousing ending. It sure paid off, considering Jaws became the first official blockbuster and chewed up the box office.

In fact, in the “Making of Jaws” feature-length documentary, available on the DVD and Blu-ray, novel author Peter Benchley recounts his conflict with Spielberg over the ending of the book versus the movie:

I said “Steven, that is completely unbelievable. It can’t happen. A shark does not bite down on a SCUBA tank and explode like an oil refinery.” He said, “I don’t care.” He said, “If I have got them for two hours, they will believe whatever I do for the next three minutes because I’ve got them in my hands, and I want the audience on their feet screaming at the end, ‘Yes, yes! This is what should happen to this animal!’”… Reality may be great and truth may be wonderful, but none of it holds a candle to believability…. His ending brought people to their feet, screaming.

SCUBA tanks are essentially metal cartridges filled with compressed air. They have a valve at the top that regulates the air at the proper pressure to the diver so he or she can breathe while under water. Simple physics tells us that anything under pressure has the potential to explode. A properly-filled standard tank has a pressure of 3000 psi. That pressure has the potential explosive energy of about 300 grams of TNT, or that of a hand grenade or two, which can be quite deadly.

While SCUBA tanks are actually very safe to use, there have been some notable failures to them. Sometimes they do, in fact, explode. Back in September 2011, Gulf War veteran Russell Vanhorn III died when his SCUBA tank exploded while he was carrying it across a parking lot in St. Petersburg, Florida. The explosion was so big it damaged vehicles up to 100 feet away and even blew out a door of a nearby car. Several other cases exist on the books, include a woman killed in Florida in 2004 when a tank she was filling exploded and an incident from 2010 when two Polish tourists were killed in Croatia.

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But Wasn’t This Myth Already Busted?

In 2005, the television series Mythbusters actually tested the results of firing a rifle into a SCUBA tank. The result was not a fireball explosion we see in the film, but instead, the compressed air rushing from the bullet hole propelled the tank like a rocket out of the shark’s mouth. The case of the exploding tank was busted.

However, while the SCUBA tank in Jaws might not have led to such a spectacular explosion, it very well might have torn a hole in the shark’s body, effectively killing it. There’s enough compressed air in a SCUBA tank to propel it with such force that it can bust through stone and concrete. In 2008, the Swiss Fire Brigade filmed tests of SCUBA tanks as projectiles to demonstrate how dangerous ruptured tanks can be.

Still, an Explosion Would Be Cool

One possible way to create an explosion for the scene is if Hooper were using pure oxygen in his tanks rather than compressed air. The oxygen, while not explosive on its own, would make everything around it instantly more combustible. In fact, some cases of real exploding SCUBA tanks are a result of pure oxygen in the mix.

However, it’s unlikely that Hooper would have used pure oxygen because he was only diving in the shallows (and he specifically tells Chief Brody they are filled with compressed air). Pure oxygen is used for deep-sea diving to avoid nitrogen (which accounts for approximately 78% of air) evolving in the blood as bubbles when the diver rises to the surface, a condition popularly known as “the bends.” (Incidentally, in the sequel Jaws 2 a diver surfaces too quickly and ends up with the bends, which may or may not be better than being eaten by a shark.)

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So, Could Chief Brody Have Done It?

In spite of what Spielberg and Benchley have said, what Mythbusters declared, and what cinemaphile know-it-alls around the internet might say, the physics behind the climax of Jaws is actually possible. It is, however, unlikely that the SCUBA tank would rupture and fracture as specifically depicted in the film (unless self-proclaimed rich child Hooper invested in sub-standard or old, deteriorated equipment, or unless he brought along pure oxygen in his tanks for uncharacteristically shallow dives).

However, if the shark tried to eat a SCUBA tank, and if that tank remained lodged in its mouth, and if Brody was able to hit a moving target approximately the size of a personal pan pizza at Pizza Hut, then at the very least, there’d be a chance the SCUBA tank projectile would rip back into the shark’s gullet and do enough damage to slow it down or kill it.

But don’t plan on hunting sharks with a SCUBA tank and rifle. Or do, and just get eaten in the process.*

*Please do not actually get eaten. Or try any of this.

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