Spice mine K76 existed as a mining operation found within the spice mines located on the planet of Kessel. The Galactic Empire transported Wookiee captives to mine K76 for the purpose of collecting spice; however, these Wookiees were rescued by the rebel team aboard the Ghost.
Within the episode The Rebellion Begins, the mine is presented under a different designation, specifically "spice mine K-seventy-seven." This designation was subsequently reiterated in the short story "The Escape," featured in the Star Wars Rebels Annual 2016, where it was designated as "spice mine K-77."