In Alastair Reynolds' "Revelation Space" universe there is no faster than light travel, and so to travel interstellar distances people are put in a form of suspended animation called "reefersleep". According to the Revelation Space wiki:

Reefersleep is a state of cryo-preservation assisted hibernation employed by Ultranauts and others intending to travel through space for extended periods of time.

The "sleep" part of the name is clear, but what does "reefer" signify? Dictionaries tell me it is a term for a marijuana cigarette, or a jacket made of thick material, neither of which seems very relevant in this context. Did Reynolds have some specific meaning in mind?

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    A reefer is also a "refrigerated trailer" used in freight hauling. That could be it because it ties into the "cryo" portion but I have no proof.
    – Skooba
    Mar 2, 2021 at 14:32
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    @Skooba I believe this is correct, although I think it might just be slang for any large industrial freezer, usually a walk-in.
    – mwarren
    Mar 2, 2021 at 14:34
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    @Skooba ahh, I didn't make the connection between "refrigerater" and "reefer". Clearly I need better dictionaries... Mar 2, 2021 at 14:48
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    @ClaraDiazSanchez I don't think it is a natural connection. My first thought when I see reefer is a connection to marijuana... but maybe that says more about me than the words...
    – Skooba
    Mar 2, 2021 at 19:49
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    @Fattie wrote: [Reefer] is a completely normal and common word that every native English speaker would use. You sure about that? Call a few of your native English speaking friends and tell them you want them to bring over reefer. Only if they are a trucker will they possibly show up with a refrigerated truck. Mar 4, 2021 at 22:42

3 Answers 3


According to the glossary on AlastairReynolds.com the reefer in reefer sleep is;

Reefer. A cryogenic sleep casket

The term reefer in this context is likely to be that refrigerated trailers (and probably other forms of large scale industrial refrigerators) are known colloquially as reefers. Since cryonics is the freezing of bodies for preservation, the relation is pretty clear.

Thanks to @fez for the link to the glossary in a comment.

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    – Valorum
    Mar 2, 2021 at 14:43
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    So the Ultranauts are not just hitting the bong so hard that they nap for 100 years.
    – Robyn
    Mar 4, 2021 at 1:46
  • the answer is completely correct but the use of "likely" is confusing.
    – Fattie
    Mar 4, 2021 at 13:07
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    @Fattie The term likely in this context is likely to be that absolute claims of fact are rarely absolutely true.
    – Yakk
    Mar 5, 2021 at 16:10
  • I'm not sure what you mean @Yakk (1) yes, it's completely normal in English that words can have more than one totally unrelated meaning (2) the question on this page is "what is the meaning of reefersleep" (3) the answer is absolutely, unequivocally, definitely, certainly, without a doubt, definitively that it means sleeping in a reefer (ie, sleeping in a refrigerated transport) (4) referring back to point 1, the two other common (unrelated) meanings of "reefer" have absolutely no, whatsoever, relationship to the question on this page.
    – Fattie
    Mar 5, 2021 at 16:13

REEFER is a contraction of "Refrigerated Container" and will keep the contents at a pre-configured temperature, often -18 degrees C for "deep frozen" items like meats. Items like fruits need to be chilled to perhaps +4 degrees C, and not frozen.

The bodywork is lined with extra insulation, and there may be humidity control systems to protect the contents. A nominal "20 foot container" or TEU will have slightly less internal capacity when it is refrigerated compared to a normal sized container due to insulation and motor. The motor is outside the storage space, its in a separate protected area at one end of the container.

Here are some stacked reefers, mixed in with regular shipping containers (also known as "sea cans")

The white ones have a motor pack visible on the end, which are connected to an all-weather power socket. This is charged as an additional cost when booking space on a vessel. Trucks also have power ports to run the motor.

The motor runs a compressor which is connected to an evaporator and condenser. There are often fans to increase airflow over both.


In the context of this story, a reefer is an ice-box or ice-coffin for preserving a living person for a long voyage. The Reefer is probably a "plug and play" unit with a lot of self-contained systems, requiring only power to function. It may have an internal power source as backup for some amount of time, or it might be independent of ship's power.

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    I've seen stacks of these at various yards; I have no idea how they get adequate airflow the way they're packed on a container ship.
    – DavidW
    Mar 3, 2021 at 0:35
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    @DavidW The individual container refrigeration systems are powered from the ship's electrical generators. Containers have reinforced pillars at each corner for supporting the weight when they are stacked, so there is a small air gap completely surrounding each container. They are not just piled on top of each other like cardboard boxes.
    – alephzero
    Mar 3, 2021 at 0:50
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    @DavidW in a ship, the containers are in stacks. Below deck there are rails to control and guide the containers to their precise landing spot, and they are designed to be bolted together in the corners. On rough voyages, diagonal braces are added before the weather turns bad. Do do so, there has to be access across the ends of the containers, and not on the sides. Thus there is a metre or so between the end of one container and the start of the next. The sides don't really matter, and the vertical edges are the main load-bearing parts.
    – Criggie
    Mar 3, 2021 at 7:26
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    @alephzero - there is a HUGE gap (like four feet) between each length-wise row of containers. ie you can walk between them. quite simply the reefer equipment, fan etc is on that open end. what you mention about a small airgap around is not relevant to how the 'fridge gear works.
    – Fattie
    Mar 5, 2021 at 16:16

Refrigerated cargo ships have been known as "reefers" throughout their 150-year history. They were initially used for transporting frozen meat, but a major specialist cargo was bananas. Since bananas have a relatively low density, the banana reefers soon began to carry passengers as well as the cargo, and by 1900 they were operating somewhat like modern cruise ships. The US-based United Fruit Company, which was the biggest shipper of bananas worldwide, had one of the largest non-military shipping fleets in the world in the early 20th century.

Many of the "banana boats" were used as troop carriers in WWI and WWII.

Modern shipping often uses refrigerated containers (powered by the ship's system) instead of refrigerated bulk cargo, but the "reefer" designation is still in use.

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    And railroad cars as well, through the whole history of using ice to keep produce and meat cool. Dates back to the 1850's.
    – Jon Custer
    Mar 3, 2021 at 18:35

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