Lake Union is one of Seattle’s most iconic landmarks. Washingtonians enjoy boating on it, living on it (in houseboats) and picnicking by it at Gasworks Park. But many people are unaware that this large lake has its own special mystery — an island once emerged here overnight. And months later, it happened again.

Lake Union is a huge freshwater lake in Seattle. It’s impossible to miss.

Kraig M / TripAdvisor The lake is about 571 square acres in total. It was named by Thomas Mercer, who correctly predicted that canals would eventually connect Lake Washington and Puget Sound in a “union of waters.”

Seattle has a bit of a history of changing its topography, from filling in the Duwamish Tidal Flats to shearing off Denny Hill.

EMcCaught / TripAdvisor But in 1962, this naturally occurring phenomenon surprised and baffled everyone.

On May 16, 1962, a mysterious island arose in Lake Union.

james / Flickr The island was made of mud and clay and measured six feet by eight feet.

A group of University of Washington students immediately ventured out to study this new development, which they named Chelan Island.

Daniel Ramirez / Flickr The island soon disappeared as quickly as it came.

Then, two months later, another island appeared in the lake, on the east side.

是一个漂亮的观景公园 / TripAdvisor This time, it was the Army Corps of Engineers who stepped in to investigate. They declared that the dumping of fill from the construction of I-5 was causing all the water displacement. However, even after they stopped the dumping, the island would occasionally make an appearance.

No islands have appeared in Lake Union since that 1962 day, and it’s still not entirely clear how it happened.

是一个漂亮的观景公园 / TripAdvisor The lake is beautiful and peaceful, but it’s also mysterious.

Did you know about Lake Union’s islands? Washington is full of strange tales.

Kraig M / TripAdvisor

The lake is about 571 square acres in total. It was named by Thomas Mercer, who correctly predicted that canals would eventually connect Lake Washington and Puget Sound in a “union of waters.”

EMcCaught / TripAdvisor

But in 1962, this naturally occurring phenomenon surprised and baffled everyone.

james / Flickr

The island was made of mud and clay and measured six feet by eight feet.

Daniel Ramirez / Flickr

The island soon disappeared as quickly as it came.

是一个漂亮的观景公园 / TripAdvisor

This time, it was the Army Corps of Engineers who stepped in to investigate. They declared that the dumping of fill from the construction of I-5 was causing all the water displacement. However, even after they stopped the dumping, the island would occasionally make an appearance.

The lake is beautiful and peaceful, but it’s also mysterious.

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Address: Lake Union, Seattle, WA, USA