While Biscayne National Park is free to enter, you need a boat to reach most spots in the park. Camping is available, but there is a $25 fee.

Biscayne National Park

Scuba diving, fishing, snorkeling, and canoeing or kayaking are all great ways to experience this maritime park, so if you don't own the equipment, you'll have to buy or rent it.

The best way to access this collection of five islands in California is by kayak or the Island Packers, a boat service that ferries to each island.

Channel Islands National Park

Prices vary depending on which island you'd like to see, and those who wish to camp on an island will see a bigger charge for transportation.

This park is in South Carolina and has one of the highest canopies in the world, thanks to its towering hardwood trees. Plenty of free tours are available.

Congaree National Park

Backcountry camping is free, but staying at a campground comes with a small fee. You can rent gear to canoe or kayak through the park's Cedar Creek.

Between Cleveland and Akron, Ohio, is a free escape into nature, with a scenic railroad, various waterfalls, and meadows full of wildlife and flowers.

Cuyahoga Valley National Park

Overnight stays are not permitted at Cuyahoga Valley National Park, but there are restaurants and places to pick up a few snacks in and around the park.

You'll have to weigh the cost of getting to this park with the benefit of the epic Alaskan scenery, as this is one of the most challenging national parks to see.

Gates of the Arctic

As one of the last completely wild places on Earth, no roads exist in the park, so be prepared to take on the millions of acres of wildlife, valleys, and mountains.