Updated posting due the tragic Arecibo Observatory collapse.
Here is a retro post from 2004 based on demand from readers.
Puerto Rico is a territory and not a separate country, but it has many interesting places to explore. A great way to visit is to take a cruise or stay at a famous hotel like the Caribe Hilton. Did you know this is where the pina colada drink was invented?
Of course, when you visit in San Juan, you have to walk/hike up to the old fort. It is historical and quite a site in the old capital city. Quite safe, scenic and many things to see and do around it along the way.
I know it is controversial, but visiting Bacardi rum distillery is fun and educational. Is it Cuban or Puerto Rican, I won’t argue, but overall a very easy place to get a quick tour and a taste of rum.
There are also some awesome hiking and cave tours you can take all in reasonable distance from San Juan. They are mostly easy, low cost guides and quite adventurous.
It is hidden in the hills outside of San Juan in the jungle. If you research a little, you can find it. There are no formal tours here, but you can hire a car to take you there. It is worth the low cost taxi price.
It is so huge, it is practically impossible to take a single picture of the radar dish unless you are flying above it in a helicopter.
It is breath taking and quite a site for science or science fiction fans to visit. Highly recommended.
They also have a great museum here. I hope it can remain and stay open despite the collapse.