Getting back on track, sure it's possible to go on Indy-esque treasure hunting expeditions. Civil War and Indian artifacts in the states, fossil hunting on private land in the states, sneaking pottery shards out of foreign countries, going on safari in Africa, jungle cruises, volunteering (i.e. paying out the wazoo) to do the heavy labor on archaeological digs.
Lots of possibilities for adventure.
Now if you're looking for treasure maps and cryptic clues, that's more for the movies, though they certainly exist as well. But then you're looking at 'professional treasure hunting' with big $$ backers paying for lots of equipment and manpower as they hope to find lost treasures. (What's the name of the island with the supposed pirate treasure and all the flood water traps, etc?)
So, just go looking for arrowheads and get some friends to shoot at you with paintball guns while you do it.