in which he also went and preached to the spirits in prison,
    Several reasons support this view: (a) Peter calls Noah a “herald of righteousness” (2 Peter 2:5), where “herald” represents Greek kēryx, “preacher,” which corresponds to the noun kēryssō, “proclaim,” in 1 Peter 3:19. (b) Peter says the “Spirit of Christ” was speaking through the OT prophets (1 Peter 1:11); thus Christ could have been speaking through Noah as an OT prophet. (c) The context indicates that Christ was preaching through Noah, who was in a persecuted minority, and God saved Noah, which is similar to the situation in Peter’s time: Christ is now preaching the gospel through Peter and his readers (1 Peter 3:15) to a persecuted minority, and God will save them. - The ESV Study Bible 