If you’ve been fortunate enough to travel along all 92 miles of Denali Park Road, you undoubtedly got a chance to take a peek at Wonder Lake, often called the Crown Jewel of Denali. This lake is often classified as a kettle lake. It’s one of the largest lakes in all of Denali National Park, and it’s the largest body of water along the park road. On a clear day, it acts as a reflection pool for the mountain. Together, Wonder Lake and Denali offer a brilliant landscape view, one of the most photographed features in the park.
While most kettle ponds are relatively shallow with depths around 30 feet, Wonder Lake is actually 250 feet deep. It is also narrow in shape at 3 and half miles long and less than 1 mile wide. Even though it’s often classified as a kettle lake, a lake as large and narrow as this one is actually significantly larger than most kettle lakes. The term “kettle lake” might not be the best way to describe it.
A kettle lake or a kettle pond is a small body of water that forms after a glacier melts. As a glacier slowly flows downhill, a block of ice can fall or break off and become buried or partially buried in the ground. When that ice block melts, it will often leave behind a small imprint that will later fill with water and turn into a kettle pond. While Wonder Lake was absolutely formed from a retreating glacier, it’s not the result of one single block of ice. It might instead be more appropriate to classify it as an inland fjord.
A fjord is a narrow inlet on the coast with steep cliffs, and they form as the result of a glacier flowing into the ocean. As a glacier flows downhill and eventually reaches the ocean, it carves out a valley in its wake. As the glacier melts, the ocean then fills in the narrow valley with sea water. If you’ve ever visited the Kenai Peninsula, you’ve likely sought out to view the myriad of fjords in that area as the dramatic sea cliffs of the Kenai fjords are a popular sightseeing destination.
While Wonder Lake does not sit near the ocean, it resembles a fjord in that a glacier carved out a narrow valley that then later filled in with water. If you look toward the bottom of Wonder Lake on a clear day, you can see bands of gravel piled up along the floor of the lake. This is evidence that Wonder Lake is actually the result of a glacier advancing and retreating over many thousands of years, pushing sediment into small berms that now rest below the surface. As the glaciers that covered the park have melted, Wonder Lake filled with water, becoming one of the largest lakes in Denali National Park.