New Junior Ranger program offers patches for Underwater Explorers./NPS screengrab.

With so many units of the National Park System tied to water, it shouldn't come as a surprise that the Junior Ranger program has a category for Underwater Explorers.

Think about it: There are four national lakeshores (Pictured Rocks, Apostle Islands, Indiana Dunes and Sleeping Bear Dunes), and ten national seashores (Cape Cod, Fire Island, Assateague Island, Cape Hatteras, Cape Lookout, Cumberland Island, Canaveral, Gulf Islands, Padre Islands, and Point Reyes). With all that water, there is lots to do and learn.

"Perhaps the best-kept secret of our National Parks is the underwater realm that they include: millions of acres of submerged lands, only a fraction of which have been explored by divers," says the Park Service. "From the geysers on the bottom of Yellowstone Lake and the coral reefs of the Dry Tortugas, the National Parks have much to offer recreational divers."

To earn an Underwater Explorer patch, kids 7 through 14 have a 36-page color publication that explores the National Park System's ocean and freshwater resources through a variety of fun activities. Some of the activities have to be done in a park, but some can be done at home. For instance, there's a home project involving how water currents work, and one that shows you how to build a coral polyp at home.

Throughout the guide youngsters will learn about such things as kelp forests, coral reefs, scuba gear, sharks, sea turtles, and many other water-related topics in an approach that offers fun and education for the entire family. There are word searches, mazes, word jumbles, and coloring pages.