Sudden Valley was originally planned in the late 1960s as a recreational subdivision on Lake Whatcom, but beginning in the early 1970s it gradually evolved from vacation cabins into a full-time residential community. Today, it is home to roughly 6,000–7,000 residents, making it one of the largest homeowners’ association communities in Western Washington.

From 1906 until about 1925, a “mail boat” operated on Lake Whatcom — delivering mail to residents living around the shoreline communities of the lake.

In the early 1900s, Lake Whatcom was served by multiple ferries, with as many as seven operating at the same time. These ferries ran regular roundtrips between lakeside communities such as Silver Beach and Blue Canyon.

Before Sudden Valley was developed, the area was heavily logged. Some of the old logging roads and stumps can still be found along trails and open spaces, giving insight into the land’s industrial past.

Lake Whatcom is the largest lake entirely within Whatcom County, stretching about 8.5 miles and covering roughly 5,500 acres.