This is a national forest that is located in Rio Grande. Only $2 per vehicle and make sure to get the tickets the day before online. It's huge so be prepared to drive a bit and hike in comfortable shoes.
This is located on the other side of the town called "Old San Juan" where most tourists stay at. There are still parts that you can check out even without a ticket so you're not missing much.
This is the route that takes you from SJU to Rio Grande area through the coast. Maps don't suggest this so make sure to select it before you start driving because other routes are just basic highways.
This is a very popular beach and located in old San Juan so expect a lot of tourists here. Besides the crowd though it is still a nice beach to visit and there's so much to do around so you won't get bored.
It's truly the most beautiful beach I have ever seen. Just remember this is on a separate island so you do need a boat of some kind and might really get lucky and end up seeing some wild horses.