From March to July, Puerto Rico becomes a makeshift nursery for hundreds of sea turtle mamas, who bury their eggs deep in the sand at select spots around the coast. Sixty days later, when the babies hatch, the mamas are long gone, but lucky travelers get to witness the little ones taking their first steps.

The humbling experience of paddling around Bio Bay under the moonless sky and seeing the waters glow and light blue is on par with chasing the northern lights or witnessing a volcano erupt: You know it's just nature, but the sheer spectacle and surreal-ness of what's happening make you wonder if maybe this is all just one big dream. Pinch yourself – it isn't.

Bio Bay may be the star attraction on this 21-mile wide island, but you haven't really seen anything until you've waded around at Red Beach, a glistening inlet of turquoise blue water set against white sand and dense forest. No need to worry about passes or permits here – every single beach on Vieques is open to the public and free.

Since Vieques' stunning beaches and woodlands were only revealed to the public in 2003 (after 60 years of on-and-off use as a military testing site), many of its gems are still unknown to travelers. One example is the starfish colony located at Rompeolas. A popular jogging spot, this pier is also a hive of marine life activity. On a snorkeling trip, we spied four full-grown sea turtles swimming by the end of the pier. Closer to shore, there's a starfish colony with a captivating array of five-legged creatures of all sizes and colors.

Over in the Rio Grande, about 30 minutes from capital San Juan, St. Regis Bahia Beach Resort is home to the Caribbean's only Audubon Society nature reserve. For those who are lucky enough to stay there, the 483-acre resort, which started out as a luxury golf course (open to the public with reservations), has grown to encompass a 139-room luxury hotel with a private beach, nature trails, and it's very own private bird sanctuary. 

If there's one thing we took away from our visit to the Rio Grande, it's the area's healthy lizard population. Slow, claw-footed lizards. Tiny, wall-clambering geckos. You name it, they're here. On our first day at the St. Regis, we watched the resident wildlife manager rescue a giant rogue specimen from the pool area. Once trapped inside the net, his green tail coiled several times over to fit inside.