How do I get to El Yunque in from San Juan Puerto Rico?

My boyfriend and I are going to San Juan in June and I am dying to see the El Yunque rainforest. However, it's about an hour away from our hotel in condado. Is there any service we can use to pick us up from our hotel? I'm getting that we have to rent a car to get there but my boyfriend and I are both 21. Will any place rent us a car being only 21? Thank you.