Star Wars: Rogue One - 11 Biggest Unanswered Questions
4. Why Was Vader In The Bacta Tank?
The Question: Darth Vader is briefly seen out of his iconic suit at his castle home, sat inside a bacta tank before meeting up with Krennic. Why was he in there?
The Likely Answer: We know that the bacta tank can help accelerate the healing of injuries (as it helped Luke after he sustained injuries on Hoth during The Empire Strikes Back), so it's possible that Vader needs to periodically visit the tank in order to stave off infections from his severe burns, or maybe he just does it for personal comfort every now and then.
It's not a big deal either way, but adds some interesting development to Vader as a character.