Impressive things to do for the summer?

I’m poor, so I’ll only be considering spending money on my flight ticket.
I’ve applied to an abroad program that offers full scholarships.
I might consider doing Duke TIP again this summer.
I’m trying to apply to the SEGL summer program where I can live near Capitol Hill in DC and sometimes meet with congressman and embassy leaders.

Some of these are highly selective.

But what can I do that will blow my mind and challenge me like nothing else?
I’m passionate about babies and healthcare and global leadership, but I don’t know where to look without going into credit debt.

Help