Tacit knowledge can never be properly expressed. Explicit knowledge , for example a map or list, is codified and put down. You can look at it, read it, run it through your mind over and over. You can see the errors, fieldcheck, refine, test. You can begin to solve puzzles, to explain things, to see what was hidden there all the time.
Explicit knowledge can be permanent, a time-capsule.
Maps and documents fade, but memory fades more. Explicit knowledge travels to others and imbues them with what you know, and how you have learned it. There is a lot of tacit knowledge in caving. A tiny bit appears in our folklore. It steers us, if we patiently seek certain people, to caving areas and to leads.