Superman The Man of Steel #104 “Bounty: Man of Steel – No Axioms” (September 2000)
In this issue, Superman & Swamp Thing pass each other like two ships in the night. Swampy only shows up in one panel but he looks great. Doug Mahnke is on pencils. Tom Nguyen and John McCrea are the inkers.
Superman and Swamp Thing are aboard the S.S. Arkham. The flying detainment facility is dubbed the UFO of irrationality. Superman is being detained for being rational.
After his evaluation from Dr Skizm, Superman is sent to the rational ward of the UFO. It’s where the “perverts—your fellow scientists and skeptical scum” are held.
While pondering his conundrum, Superman wonders the rational ward. While doing so, he passes Swamp Thing whose getting advice.
Two inmates suggest to Swamp Thing that he try aromatherapy and psychotherapy (rebirthing) for what ails him. The rebirthing suggestion is funny, knowing that Swamp Thing can regrow himself anywhere he pleases.
This Swampy cameo is surely an appearance for fun and doesn’t affect Swamp Thing continuity. This book was published the same month as, Swamp Thing #5 “Burning Down the House” (Series 3). At this time, Swampy was taking a break from the comic book kingdom for the most part. Around this time, he only showed up in brief cameos and books based on Elseworld stories. You can reference the Vertigo Era: ’93-’10 appearance list, here.
But, it would be fun to imagine how and why Swamp Thing would allow himself to be held captive on the ship.