This gorgeous lake was once a mountain. What’s so special about Crater Lake National Park.

There are plenty of stunning lakes across America, but none like you’ll find at Crater Lake National Park in Oregon.

Its namesake lake is the deepest in the country, with an average depth of 1,943 feet, according to the park.

In addition to being mind-bogglingly deep, Crater Lake boasts extremely clear water. It's famously blue and rarely freezes over, which makes the lake a spectacular sight year-round, though visitors may want to plan for certain months in particular.

Here’s what you should know about Crater Lake, the latest park in USA TODAY’s yearlong series, which began with Acadia and will end with Zion.

What's so special about Crater Lake?

Crater Lake actually started as a mountain, Mount Mazama.

A volcanic eruption roughly 7,700 years ago caused the mountain to collapse inward over time, forming a volcanic crater, the park says.

Archaeologists have found evidence of Native Americans who camped but did not appear to settle on the mountain before it erupted. The park notes the area is considered sacred to Indigenous tribes in Oregon and California.

According to the park’s website, “Makalaks (now Klamath Indians) held the belief that this place was so holy that looking upon it would lead to death.”

Is Crater Lake one of the Seven Wonders of the World?

No, but Travel Oregon, the state’s official tourism arm, has dubbed it one of the 7 Wonders of Oregon.

How far is Crater Lake from Portland?

Crater Lake National Park is about four hours away from Portland by car.

The park is in southern Orgeon, near Klamath Falls. The nearest airport is Rogue Valley International-Medford Airport.

How long does it take to visit Crater Lake?

You can easily spend a full day at the park, but visitors who are tight on time can drive along its scenic Rim Drive in about two hours, with stops along its 30 overlooks for sightseeing, according to the park.

Free national parks for families: How to visit with Every Kid Outdoors

What is the best month to visit Crater Lake?

The answer depends on what you’re looking for.

Crater Lake has two main seasons: winter from November through April and summer from July through September, according to the park. They’re both beautiful in their own way, but summer is busier, and just about everything in the park is open and operating.

The park says openings and closings are not as predictable in May, June and October, but the park itself is open all year.

Can you swim or fish in Crater Lake?

Swimming is allowed in some areas, but visitors should note there are no lifeguards and the water is cold: surface levels are 38 to 62 degrees depending on the time of year, according to the park.

Fishing is allowed in Crater Lake and all streams except Lost Creek and Sun Creek, where native bull trout live. The species is considered threatened and protected under the Endangered Species Act. No fishing permits or licenses are required.

What are some fun facts about Crater Lake?

Crater Lake is not connected to any other bodies of water. Its water comes from millennia of rain and snow. “With an annual average of 43 feet of snow, Crater Lake is one of the snowiest places in United States,” the Interior Department says.

There's an old man in the lake. OK, not really ? but a 30-foot-long mountain log called the Old Man has been floating around the lake since at least 1896, according to the park. A peculiar thing about the Old Man is it floats vertically.

Among the park’s wildlife, there is one species you’ll find only in Crater Lake: the Mazama newt, a subspecies of rough-skinned newt more common in the Pacific Northwest, according to the park and Department of the Interior.

This article originally appeared on USA TODAY: Crater Lake wasn’t always a lake. Fun facts about the national park.