There is ample to muse about in 1 Peter 3.18, 19 & 20.
Writing about Jesus, Peter tells us that Jesus was:
put to death in the flesh but made alive in the spirit, in which he went and proclaimed to the spirits in prison, because they formerly did not obey, when God's patience waited in the days of Noah…
Jesus went to preach to a certain group of no-long-alive people? Those who were in that first world-wide swimming contest of who could swim the longest?
Why to them?
Looking at it through my very subjective perspective as a missionary/pastor/preacher, I’ll go on record as suggesting that it was because they were the first people to have a preacher of righteousness speaking out the truth to them.
I refer to 2 Peter 2.5:
[God] did not spare the ancient world when he brought the flood on its ungodly people, but protected Noah, a preacher of righteousness…