"Smoke on the Water" is a famous and influential rock song by Deep Purple.

The song is known for and recognizable by its central theme, a crunching four-tone minor key blues progression (I-III-IV with a passing flat V) that is perhaps the single most famous riff in heavy metal music history. The riff is properly played without a pick, using two fingers to pluck two adjecent strings held in a IV interval. The riff, played on electric guitar by Ritchie Blackmore, is immediately joined by drums and contrapuntal electric bass and organ parts before the start of Ian Gillan's expressive vocal. Despite the heaviness of the guitar part, constant movement and interplay within the supporting parts keeps the feel of the song from becoming leaden. The song's structure takes a contrasting verse-chorus form, with the driving verse sections building musical tension while the soaring chorus releases it.

The lyric of the song tells a true story: on December 7, 1971, Deep Purple had set up camp in Montreux, Switzerland to record an album using a mobile recording studio (rented from the Rolling Stones and known as the Rolling Stones Mobile Studio) at the entertainment complex that was part of the Montreux Casino (referred to as "the gambling house" in the song lyric). On the eve of the recording session a concert featuring Frank Zappa and the Mothers of Invention was held in the casino's theater; during the concert a fire broke out (said to be caused by a Swedish fan shooting a flare gun in the ceiling) that eventually destroyed the entire casino complex, along with all the Mothers' equipment. The "smoke on the water" that became the title of the song referred to the smoke from the fire spreading over Lake Geneva from the burning casino as the members of Deep Purple watched the fire from their hotel across the lake. The "funky Claude" running in and out is referring to Claude Nobs, the director of the Montreux Jazz Festival who helped some kids while the casino was burning.

Left with an expensive mobile recording unit and no place to record, the band was forced to scout the town for another place to set up. One promising venue was a local theatre called The Pavilion, in an effort to capture a reverberative sound; but soon after the band had loaded in and started working/recording, the nearby neighbors took offense at the noise, and the band was able to lay down backing tracks for only one song before the local police shut them down.

Finally, after about a week of searching, the band rented out the nearly-empty Montreux Grand Hotel and converted its hallways and stairwells into a makeshift recording studio, where they laid down most of the tracks for what would become their most successful album, Machine Head.

Ironically, the only song from Machine Head not recorded in the Grand Hotel was "Smoke on the Water" itself; the basic tracks for the song had been the only things recorded during the aborted Pavilion session.

"Smoke on the Water" was included on Machine Head, which was released in early 1972, but was not released as a single until nearly a year later (the band has said that they did not expect the song to be a hit); the single would reach #4 on the Billboard pop single chart in the U.S. in the summer of 1973, and propel the album to the top 10. Live performance of the tune, featuring extended interplay between Blackmore's guitar and Jon Lord's Hammond organ would become a centerpiece of Deep Purple's live shows, and a version of the song from the live album Made in Japan became a minor hit on its own later in 1973.

During Ian Gillan's stint with Black Sabbath in 1983, they performed "Smoke on the Water" as a regular repertoire number on encores during their only tour together.

The song was notably performed by Señor Coconut at The Big Chill in 2004.