Let's just say a hippie like kid just got out of highschool, and doesn't count on the world being here for too long. Keep in mind this kid may be stupid, but he just needs suggestions.
Let's say he takes out a $50,000 college loan or something like that. This kids goal is to see the most amazing things this world has to offer, mostly natural and nature related things.
Some ideas i have so far..
Northern lights: Must do, just amazing.
National parks?
Island?

Post your ideas here.

How about the Great Barrier Reef and then a trip up to Papua New Guinea.

Or, start from the east coast of Brazil in a boat and travel westward until you reach the Pacific ocean in Peru or Ecuador.