Although public transportation exits in the greater San Juan area, its almost impossible to travel the rest of the island without a rental car. If you are under 25 (as I was last year) it cost $210 for a five day economy car rental. Split between two that's not too bad. If you are under 25 then your in luck, it will save you almost 1/2 that amount. We rented from Popular Auto in San Juan, they were very nice and they never tried to cheat us. I have heard many stories of companies charging extra for things that were not even in the agreement. They spoke no English at Popular Auto so knowing Spanish is a must if you want to use them. That said there are many other places to rent from, Popular Auto just seemed to be the lease expensive.
In San Juan we stayed at The Palace Hostel, its a bit out of the main part of the city, but it is still walkable. We drove from San Juan to El Yunque National Park, we explored this area for a couple hours before heading over to Fajardo to check into the Moonlight Bay Hostel. I recommend this place highly, they were very nice, they even went out of the way to make a veggie burger for me. The hostel is very close to the ferry terminal to head over to Isla Culebra. That evening we went on the Biobay kayak tour, if you are student you can get a discount, it only cost 35. It was an adventurous 3 hours of bumper kayaks. We maneuvered our way through small channels without any lights bumping into each other and trees until we finally reached the biobay. Although the biobays are a bit overused, and the plankton that create the color are dieing due to too much human traffic to the area we were still able to see the water light up. The best way to see the biobay is on kayak, it has less impact on the species than motor boat.
After a good sleep (4hours) we woke up to get in line to buy tickets for the ferry. No matter how much you try to negotiate with the people at the ticket office, you still have to wait until the day of your trip to buy the tickets. We were able to get on the first ferry to Culebra. The ferry takes about 1 hour each way. Its a relaxing ride, it was so relaxing that I feel asleep.
In Culebra we reserved a camping site on Flaminco Beach. You can do this over the phone, you might have to call a bunch before you can actually get a hold of someone, again another reason to know Spanish. It was $25 for a camping site and you can split it by up to 6 people. It was just Stephanie and I, but it was still cheap. Make sure to bring your own tent, you can rent one, but its much more expensive. Also during spring break, most of the college students also go to camp at Flaminco, ask for the last camp ground, I think its letter E, this one is the quietest.
We headed to Zoni Beach which is the most beautiful beach that I have ever been to. There were not too many people, unlike Flaminco, it was a very open long beach with white sand and clear blue water. Across from Zoni Beach is the Island of Culebrita. Whether you are snorkling, paddle boarding, kite surfing, or just laying out in the sun, Zoni Beach is the best place to do so.
After a wonderful small party on Flaminco Beach at night and a restful (wink) sleep in our tent we woke up the next day and walked to Tamarido Beach, it a long hot walk, and there is a part with a hill, but it is doable. We rented snorkeling equipment at Flaminco Beach camp ground, it was $10 per person for the day. It was here that we swam with the turtles. There is lots of awesome coral and neon color fish here that you can chase after. The sand is not as white as Zoni but there is much more shade. Remember to bring your sun screen.
After a long day of snorkeling and bathing in the sun we packed up our tent and headed back to the main island of PR. We were shocked at how safe it was to keep out items at the campground. We left most of our other belongings in our rental car in Fajardo. The ferry ticket is $4.50 both ways.
In all its not very expensive to travel around PR and have a good time.