Someone who is knowledgeable is highly educated and well versed in a particular subject. Making it your life goal to become knowledgeable about naked mole rats might not win you the Nobel Prize, but it might be fun.
It’s interesting to note the shift in meaning of the adjective knowledgeable from when it was first recorded in the 1600s and now. Originally, knowledgeable was spelled without the second -e, and meant “capable of being known, recognizable.” Now, though, we use the adjective to describe that which has or displays knowledge. If you're well-read and alert, you're knowledgeable about the ways of the world.