My husband and I took the ferry from Fajardo over to Culebra for a day. First, the Ferry. We read that it can be difficult to get tickets, so we arrived an hour ahead of time. While there were many people there, we were able to get tickets. Note that if you ar a senior citizen, are pregnant, or are traveling with an infant, they will put you in a separate gate area to wait (with seats, instead of standing), and will get priority boarding. We chose a spot near the front of the ferry, but learned that the waves feel rougher up front. If you are prone to seasickness, sit near the back and watch the horizon.
Upon disembarking, there were a number of tour guides with signs advertising kayak and snorkel tours, jeep rentals, etc. Thinking we'd have lots of options, we sat down at a little cafe and had breakfast. Within half an hour, though, everyone had cleared out and the tours were filled up. So if you haven't made plans in advance, as we hadn't, get on one of those tours right away! Otherwise, your options are more limited.
We ended up renting bikes and snorkeling gear and biking to Flamenco Beach. The lady in the dive shop told us this was the easiest ride to the beach. The road was paved and we found the beach easily, although I had a bit of a rough time on the steep hills coming back since I'm pregnant and have less lung capacity than usual! A better bet would have been a jeep or golf cart, which we will do next time.
At the dive shop, they pointed us to a hidden gem of a snorkeling spot, Tamarindo Grande and Carlos Rosario Beach (I think), accessible by a 20 minute hike from the parking lot at Flamenco Beach. In the back left corner of the lot, you will see a sign that says "Danger, Do Not Enter." Ignore it, squeeze through the fence, and hike 20 minutes to a secluded reef. You will come out first at Tamarindo Grande, where you can enter the water straight ahead and swim left along the reef. For deeper sea snorkeling, keep going along the path (just a few more minutes) to Carlos Rosario Beach. Again, go in and swim left.
The snorkeling was excellent, like a tropical aquarium, with brightly colored fish and plants. We loved it! If we had more time, we would have explored a second dive spot that we were told was accessible via a taxi from Flamenco Beach, where you can apparently see baby sea turtles and stingrays.
Overall, we enjoyed our stay but would have liked to have planned ahead for a jeep rental so we could see more. We took the 5:00 p.m. Ferry back, but would have enjoyed staying over for a night so that we could explore more of the island.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.