In The Voyage Home, Kirk and crew spent so much time on past Earth only because of unavailability of a strong water tank. They even messed with the history which could be dangerous.

But, the question is: Why did they need a water tank in the first place? Whales are mammals which can breathe without water. Only their movements would have been compromised for a short time.

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    As far as I know those stranded whales suffer - a lot. Even though technically possible for a short duration, you might as well ask why they let dr taylor on the ship and not tie her to the exterior with some space suit. And if anything goes wrong they end up with a dead whale. But Maybe ask over at biology?
    – Raditz_35
    Commented Feb 28, 2018 at 8:13
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    and why did it have to be transparent?
    – ths
    Commented Feb 28, 2018 at 9:12
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    The water tank wan't made from transparent aluminum, but from some strong 20th century material. Scotty trades the formula fro transparent aluminum for the material to build the tank. Commented Feb 28, 2018 at 9:15
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    Worth mentioning that they were bringing the whales back to speak on the planets behalf. Probably best to make them as comfortable as possible for the journey so they don't just say, "Yeah, humans suck. Nuke it from orbit, it's the only way to be sure. "
    – Paul
    Commented Feb 28, 2018 at 13:01
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    @Nasha I'm pretty sure the reason they got into this mess is because a bunch of whales piloting a space ship showed up.
    – Racheet
    Commented Feb 28, 2018 at 15:28

4 Answers 4


Inertial dampers aren't that reliable

Without water, a zero-gravity environment would still have been dangerous for the whales.

In the absence of water, the whales would have needed null gravity within their chamber to keep from collapsing under their own weight. Without water to hold them in place, the whales would then have been vulnerable to buffeting. Even gentle maneuvering of the ship could drive two unsecured, multi-tonne squishy masses into the bulkheads, and the slingshot around the sun involved extreme acceleration and potentially violent maneuvering. As Star Trek has shown numerous times when bridge crews are thrown about, ships' inertial dampers can reliably cope with steady acceleration but not with sudden lurches.

Around the midpoint of the previous film, Enterprise attacks the same Klingon Bird-of-Prey. The Klingon bridge crew are jostled in their seats, and their reactions seem out of proportion to the bridge console explosions, which suggests that the entire ship is lurching:

In "Redemption, Part 1", a rebel Klingon vessel fires a torpedo at Gowron's flagship. The impact shakes Gowron (foreground, seated) and nearly knocks a standing bridge officer (background) to the deck. As the attack proceeds, the flagship continues to shake:

In The Voyage Home, Scotty undoubtedly could have cobbled together some sort of active restraint system using tractor beam emitters, but he was working with a limited supply of equipment and an unfamiliar programming interface. Water, as a passive restraint, was the safest option.

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    As Star Trek has shown numerous times ... on Federation starships. Do they ever show similar engineering faults in a Klingon warbird? Commented Feb 28, 2018 at 16:27
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    @RoddyoftheFrozenPeas I'm pretty confident you can find some examples in DS9, though I don't know off-hand for sure.
    – jpmc26
    Commented Feb 28, 2018 at 17:13
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    @RoddyoftheFrozenPeas I bet you could find some in A Matter of Honor (TNG).
    – hobbs
    Commented Feb 28, 2018 at 19:10
  • @RoddyoftheFrozenPeas - I added a video clip from The Search for Spock. It looks to me as if the Klingons are being shaken, not just startled by the explosions, but I admit that it's not clear. I'll try to find a better example.
    – Gaultheria
    Commented Feb 28, 2018 at 20:50
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    @jpmc26: Forget Klingon vessels, I'm pretty sure DS9 has at least one Jem'hadar screen shake, and their tech is way more advanced than any mere Alpha Quadrant power.
    – Kevin
    Commented Feb 28, 2018 at 21:43

According to this website, whales need water to:

  • Support their weight and prevent their own organs from collapsing in on themselves.
  • regulate body temperature / prevent overheating.
  • remain hydrated.
  • Movement (as you already pointed out, though not really relevant in a tank the size of a fish-bowl).
  • Food consumption (again, not very relevant here).
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    A whale out of water can't fully inflate their lungs, their lungs fill with fluid and they drown in a matter of hours. Even if something the size of a fully grown humpback survives stranding for 6-12hours, there's no guarantee they'll fully recover from the experience. Commented Feb 28, 2018 at 15:52
  • In short, because it's the safest way to do it.
    – jpmc26
    Commented Feb 28, 2018 at 17:21
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    Also imagine how the whales would have felt after such torture, they would probably tell the probe to obliterate their awful human taxi drivers
    – PlasmaHH
    Commented Feb 28, 2018 at 17:37
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    The "prevent overheating" seems particularly important, but I'm guessing it could be compensated for by not heating their chamber as much as you would for a human. Two of the other issues could be handled by turning off the artificial gravity in their chamber.
    – T.E.D.
    Commented Mar 1, 2018 at 15:50

In short, it's because Kirk doesn't know how long their return journey will take. There's an extra piece of the dialogue (between Kirk and Scott) missing from the film that was apparently in the early shooting script and made it into the official novelisation

"Humpback whales. They're fifteen or sixteen meters in length. They'll mass about forty tons."

"They willna have much room to swim."

"It doesn't matter. They won't have to stay in the hold for long. I hope."

While Kirk is hoping they'll have a short uneventful trip back to the future he's anticipating the possibility that something will go wrong and they may end up spending more than a few hours with the whales in the hold, something that would be catastrophic for their health

  • This quote explains the reason why it doesn't matter to Kirk that the tank is small as being that he hopes the trip will be short. I don't take it to mean that they're using a water tank because the trip might be long, although it doesn't preclude that possibility. Commented Mar 1, 2018 at 14:07
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    @DarrenRinger - The "I hope" is the key phrase here.
    – Valorum
    Commented Mar 1, 2018 at 14:15
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    While I agree that Kirk clearly indicates he's planned for the possibility of a longer trip, nowhere from the quoted passage am I able to infer that this is the reason for using a water tank in the first place. As I read it, the necessity of a tank for a trip of any duration is a foregone conclusion by both parties and left unexplained. Commented Mar 1, 2018 at 14:59
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    @DarrenRinger - There's also the fact that Kirk isn't an expert in whales. He knows that they're aquatic and assumes that they'll need a big tank filled with water to transport them.
    – Valorum
    Commented Mar 1, 2018 at 15:03

Counterpoint, unsupported (as far as I know) by canon: It's for the acoustical properties.

One might recall that the whole point of kidnapping the whales in the first place was to get them to respond to an alien message.

Putting the whales into a water medium is important for both the whales' ability to hear and understand the message and for their ability to respond vocally.

As sensible as this seems to me and real-world physics, I don't think it has any actual canon support.

  • This answer makes zero sense. The water was to transport them safely on the ship, not to allow them to hear the alien probe while they were in space.
    – Valorum
    Commented Feb 28, 2020 at 19:38

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