Washington may not be the largest state in the nation (we rank 18th, in case you're wondering), but we've still got an impressive amount of territory you'd have to cover if you wanted to see it all. That's why it should come as no surprise that we've got plenty of secret hiking trails, lakes, eateries and other attractions that most people who live here aren't even aware of.

If you've never heard of a few of these places, you're not alone.

1. Ape Cave, Skamania

You'll find the Ape Cave on the south side of Mt. St. Helens, and with 2.5 miles of dark explorations, it's a must-see for the adventurous. The cave is the longest continuous lava tube in the continental United States.

2. Stehekin

Did you know there's a town in Washington that's only accessible by hike, seaplane or ferry? Stehekin is the perfect place to relax.

3. Casa Luna, Poulsbo

If you're ever exploring Poulsbo, Washington's little Norway, you'll probably walk right past this hidden gem. Hidden down a narrow alley reminiscent of Spain, it serves tasty classic Mexican dishes.

4. Fragrance Lake Trail, Bellingham

Whatcom County is full of beautiful nature trails, and Fragrance Lake is a perfect 4.2-mile loop that remains remarkably uncrowded throughout most of the year.

5. Cedar Creek Treehouse, Mt. Rainier

You may be surprised to learn that there's a treehouse available for overnight stays at Mt. Rainier. And while the family is currently taking a break from renting it out to the public, it's something to keep in mind for the future.

6. Madison Creek Falls

Located near the Elwha River west of Port Angeles, this waterfall is easily accessible from a short, paved path.

7. Needle & Thread, 1406 12th Ave. Seattle

The idea of anything being "hidden" in Seattle is kind of a joke -- but this secret speakeasy pulls it off. You'll find it hidden above Tavern Law in the Capitol Hill neighborhood, but you typically need a reservation to even see it.

8. Normandy Beach Trail

Normandy Park's Marine View Beach Park is a hidden gem so serene, you'll never guess you're only a few miles from Seattle. This trail is a relaxing 1.5 mile loop with water views.

9. Gardner Cave, Metaline Falls

To most Washingtonians, the Metaline Falls area (Northeast Washington) is somewhat of a mystery. You'll find this cave inside Crawford State Park, but you'll have to explore it between May and early September.

10. Ginkgo Petrified Forest State Park, Vantage

Our petrified wood forest has over 50 different species of fossilized wood, which is pretty impressive. You may have passed it by numerous times when driving to and from Spokane or other Eastern Washington spots.

If you live in Washington, you should make it a point to explore as many hidden gems as possible. Here are a few of our most beautiful hidden waterfalls.