What do you mean when you say you can't think about it rationally? There are enough survivable experiences physiologically similar to death that we can make some pretty good guesses as to what the experience leading up to it is like. And it would be incoherent to talk about the experience of being dead, because it is no experience at all (as before we were born). We know quite a bit about what happens when we die, and we have literally billions of exemplars of the event. I would say in almost every meaningful way we can think about it fairly rationally. (Whether we choose to is another question.)
But they aren't "death" death, like Whoopi Goldberg would say. You can't comprehend something that requires your consciousness to cease to exist in order to fully comprehend it.
In other words, "we" have some abstract ideas about what happens when "we" die, but it's fundamentally impossible for you, the individual, to imagine what happens when _you_ die.
>What do you mean when you say you can't think about it rationally? There are enough survivable experiences physiologically similar to death
That makes no sense. There are some experiences of coming close to death, or what doctors consider death -- which is the mind/organs shutting down, etc.
There is (and can't be) no experience of actual permanent death though, nor has a dead person recounted their experience while a dead person.
The ones retelling the experience are always alive when they do it.
Of course. But I would think the experience of falling into a coma after a hypoxic event would convey all the same conscious experiences of death. That would be what it would feel like, until you were unconscious. Then, by definition, you would feel no more.