This article refers to the early and often used Apostles Creed; it is so worth preaching:
…but before his resurrection, Jesus “descended to the dead.” The Athanasian Creed of at least a century later is more explicit, Christ “descended into hell.” Depending on context and translation Jesus either journeyed to Sheol, Hades, or Hell. But allowing for differences in language Christianity held—and technically still holds as a central tenet—the view that Jesus spent the gap between his death and resurrection “harrowing” Hell, that is journeying to the underworld to liberate the imprisoned souls of the Hebrew patriarchs who had been imprisoned there since their deaths.
Contemporary congregations will often translate “hell” into a more palatable “death” or “the grave.” There is something unseemly in the idea of Jesus among the murders, rapists, fornicators and heretics of Hell. And yet it was central to Christological accounts of salvation for two millennia that God Himself be present in the lowest rung of creation to justify redemption for all mankind.
Holy Saturday was a day in which God was not in His heaven, but rather in his Hell.
From “Jesus Went to Hell” in the RD here.