Superunknown is the fourth studio album by American rock band Soundgarden, released on March 8, 1994, through A&M Records. It is the band's second album with bassist Ben Shepherd, and features new producer Michael Beinhorn. Soundgarden began work on the album after touring in support of its previous album, Badmotorfinger (1991). Superunknown captured the heaviness of the band's earlier releases while displaying a more diverse range of influences.

Superunknown was a critical and commercial success and became the band's breakthrough album. It debuted at number one on the Billboard 200, selling 310,000 copies in its opening week and reached high positions on charts worldwide. Five singles were released from the album: "The Day I Tried to Live", "My Wave", "Fell on Black Days", "Spoonman", and "Black Hole Sun", the latter two of which won Grammy Awards and helped Soundgarden reach mainstream popularity. In 1995, the album was nominated for the Grammy Award for Best Rock Album. The album has been certified five times platinum by the RIAA in the United States, has sold 9 million copies worldwide and remains Soundgarden's most successful album. In April 2019, Superunknown was ranked No. 9 on Rolling Stone's "50 Greatest Grunge Albums" list.

Soundgarden began work on the album about two months after finishing its stint on the 1992 Lollapalooza tour.  The individual band members would work on material on their own and then bring in demos to which the other members of the band would contribute.  Frontman Chris Cornell said that the band members allowed each other more freedom than on past records.  Thayil observed that even though the band spent as much time writing and arranging as it had on previous albums, it spent a lot more time working on recording the songs.[ After two albums with producer Terry Date, the band decided to seek another collaborator, as guitarist Kim Thayil said, "We just thought we'd go for a change." Eventually they settled on producer Michael Beinhorn, who "didn't have his own trademark sound which he was trying to tack on to Soundgarden" and had ideas the band approved.

The album's recording sessions took place from July 1993 to September 1993 at Bad Animals Studio in Seattle, Washington, as according to Cornell "there was never a decent studio in Seattle and now there's one with a Neve console, so it seemed obvious to use it". Bad Animals' resident engineer Adam Kasper, who went on to produce Soundgarden's following albums, assisted Beinhorn on the recording process. Soundgarden took the approach of recording one song at a time. The drum and bass parts were recorded first for each song, and then Cornell and Thayil would lay down their parts over top. Cornell said that getting to know Beinhorn contributed to the length of time Soundgarden spent working on the album. The band spent time experimenting with different drum and guitar sounds, as well as utilizing techniques such as layering, resulting in an expansive production sound. Cornell said, "Michael Beinhorn was so into sounds. He was so, almost, anal about it, that it took the piss out of us a lot of the time ... By the time you get the sounds that you want to record the song, you're sick and tired of playing it." Beinhorn tried to add many of his preferred musicians to mold the band's sound, in what Billboard described as "weaning the band from brute force, giving it the impetus to invest in a more subtle power". For instance, prior to recording the vocals of "Black Hole Sun", Beinhorn made Cornell listen to Frank Sinatra.

Superunknown lasts for 15 songs clocking on approximately 70 minutes because according to Cornell, "we didn't really want to argue over what should be cut".  Soundgarden took a break in the middle of recording to open for Neil Young on a ten-day tour of the United States. The band then brought in Brendan O'Brien to mix the album, as Beinhorn felt the band needed "a fresh pair of ears"; O'Brien had come recommended by Pearl Jam guitarist Stone Gossard. Thayil called the mixing process "very painless",  and bassist Ben Shepherd said it was "the fastest part of the record". Read more