Any list of must-see scientific destinations would be remiss without mentioning the amazing diversity of marine life living just off the United State's coasts, and there are few better places to see that wildlife in person than Washington's Olympic Coast. Stretching 73 miles (117 kilometers) along the Pacific Ocean, the Olympic Coast sanctuary is protected completely from commercial development. Visitors can enjoy fishing, camping and whale watching among other activities, all in a protected natural environment in which marine life is thriving. Harbor seals and gray whales are common sights, and more than 300 species of birds populate the coast and the nearby Olympic National Park [source: NOAA].
Experienced adventurers can even take guided diving expeditions or kayaking trips in the sanctuary, but cold water temperatures and notoriously unpredictable weather can make those activities dangerous for anyone lacking experience. The less adventurous can take in the Makah Museum or go on a guided hike to Cape Flattery. Even if you stick to the shore, it's easy to appreciate the harmony among the refuge's fish, birds and other marine animals. No wonder millions of people visit the sanctuary every year [source: NOAA]. Of course, there are a couple of places in the U.S. that get even more visitors every year, and the next destination on our list is one of them.