El Yunque, which gets its name from an Indian spirit Yuquiye meaning 'Forest of Clouds', features over 240 species of plants and wildlife, waterfalls, streams and hiking trails leading to enticing tropical locations.

There are many ways to see the rainforest but this Hiking Tour excursion will have you viewing typical native towns until you begin your ascent by bus on a modern road through rapidly changing vistas of amazing vegetation, tree orchids, giants ferns, wild flowers, tropical hardwoods, spectacular waterfalls, and views of the entire northeast coast.

You'll stop at the most beautiful photographic sights - Jokahu Tower, hike to La Mina (35 minutes each way) then and swim or dip the cool water of La Mina Falls (10 minute stop). Make sure you have a good breakfast before this tour!

Come aboard Captain Duck Tours for the best 90 minutes you will spend on your Puerto Rican vacation!

As San Juan's only land and sea adventure, this is the most exciting way to tour this historic seaport city.

The versatile Duck boat is also a bus, and it offers up-close land and sea views of many of San Juan's major attractions!

This tour takes you from San Juan, to Northwestern Puerto Rico, part of the third largest underground river cavern system in the world. You'll enjoy a safe, guided tour of the marvels. From sinkholes and cathedral-like caverns to views of the mysterious river and its eons-old stalactites and stalagmites. Be sure to wear comfortable, non-slippery shoes! This tour also takes you to where you will see the largest radar/radio telescope. Operated by Cornell University, the telescope probes the ionosphere, examines planets and monitors natural radio emissions from distant galaxies, pulsars and quasars.

The caves at Camuy are actually 45 million years old, but it took a few million years for nature to adorn their towering ceilings with crystalline stalactites, their walls with flowing stone tapestries and their floors with mushroom mounds of stalactites. Few cave systems in the world are as massive or dramatic as the Rio Camuy Cave Park; none has a thundering tropical river transversing countless miles of uncharted channels. Three crater-like sinkholes and one cave of the huge system in the park are open to the public and they are truly memorable experiences.

The Arecibo Observatory is nestled in the mountains of northern Puerto Rico, about 30 minutes from Arecibo and is the world's largest radar/radio telescope. Here scientists from all over the world use a giant 305 meter diameter dish to listen to the universe. You may view the huge telescope from an observation platform, where its austere metallic symmetry shimmers in dramatic contrast with the dense, green, tropical landscape.