Largest inhabitable volume in space

Question

When you look at space ships, capsules and stations, one thing that is lacking in space is… space. As in: pressurized volume a human can freely move in. Most are tiny tin cans.

So I was wondering, what is or was the largest single pressurized volume ("room") in space? By this I mean the undivided volume an astronaut/cosmonaut could move around in freely.

So far, I have found these candidates via Wikipedia, but the data seems incomplete/imprecise sometimes.

• The prime candidate is the Orbital Workshop module of Skylab. Wikipedia lists a habitable volume of 302 m³ (diameter 6.6 m, length 14.7 m). But it seems this was divided up, so the actual volume a human could move around in freely was smaller. How much?
• It seems no early russian space station came even close.
• Mir was a large station by pressurized volume (around 350 m³), but it was divided into small modules and it was very cramped.
• The ISS is the largest object ever put in space (AFAIK) and Wikipedia lists a pressurized volume of 931.57 m³ as of 2016-05-28. But again, it's divided into smaller modules.
  • It seems the largest "room" on the ISS is the Kibō module with a pressurized volume of about 155 m³ (diameter 4.39 m, length 11.19 m).

So what was the volume an astronaut was able to move around in freely on Skylab? Was it the largest volume, is Kibō's volume actually large or did I miss a station/vehicle?

(Sidenote: I was thinking about the Space Shuttle at first, but while its cargo bay had a volume of about 260 m³, it wasn't pressurized.)

Answer 1

So far (2016) the biggest "room" in orbit was the Orbital Workshop of Skylab.

Here's a video showing astronauts moving in the largest part of Skylab. You never get to see the "floor" in this one, unfortunately. The room was so big that they were even able to test an astronaut maneuvering unit (jetpack) inside (see pictures at the end of this answer).

I found numbers for the Orbital Workshop volume ranging from about 270 m³ (9,550 cubic feet) to about 302 m³ (10,664 cubic feet) (total habital volume of the station is usually cited as 351–361 m³). That seems to include the crew quarters section. When looking at the cutaway diagram I estimate that the crew quarters sections (divided from the rest of the lab by a wire mesh grid) took up about a fourth of that volume, leaving the main "room" with about 202–226 m³.

The largest module (on the inside) of the ISS is the Kibō module with a pressurized volume of 155 m³. So Sklyab beats that.

Skylabs large volume actually caused problems: apart from the obvious "getting stuck" issue (Skylab crews learned that you can indeed "swim" in the station) it seemed that the large volume contributed to Space Adaptation Syndrome (citation needed; I read about it recently but can't find a good source now).

Images from the actual Skylab:

Image from trainer:

_{(source: nasa.gov)}