There is a room for confusion and speculation what happened while Jesus was in Hades.
Hades is the realm of the deceased, disembodies spirits, not hell, because hell has not begun yet.
Here is my understanding:
1) Jesus defeated death and took the keys of Hades
Revelation 1:17-19 English Standard Version (ESV)
17 When I saw him, I fell at his feet as though dead. But he laid his right hand on me, saying, "Fear not, I am the first and the last, 18 and the living one. I died, and behold I am alive forevermore, and I have the keys of Death and Hades. 19 Write therefore the things that you have seen, those that are and those that are to take place after this.
(I chose the ESV for a change because the KJV translates Hades with Hell)
2) Jesus preached to those where were disobedient during the ministry of Noah
1 Peter 3:19-20 By which also he went and preached unto the spirits in prison; 20 Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water.
This must have happened in a part of Hades reserved for the unrighteous.
3) I believe he also went to those who were in Abraham's bosom - that is the dwelling place of the deceased righteous ones who died believing God, but did not know Christ.
He released captives. (KJV says led captivity captive, which does not quite make sense to me, so I took the ESV)
Eph 4:8 Therefore it says,
"When he ascended on high he led a host of captives,
and he gave gifts to men.”[a]
9 (In saying, "He ascended,” what does it mean but that he had also descended into the lower regions, the earth?[b] 10 He who descended is the one who also ascended far above all the heavens, that he might fill all things.)
Christ then took those pre-deluge prisoners who responded to his preaching and those OT saints that did not know Christ and took them to paradise - the same place he promised to the dying thief.
There is evidence for that in Mat 27
52 And the graves were opened; and many bodies of the saints which slept arose,
53 And came out of the graves after his resurrection, and went into the holy city, and appeared unto many.
Does anyone have more revelation on this topic or can point me to some good sources of information?