A 19-year-old has gone missing during a late-night boat trip with friends on Lake Washington near Seattle. The Mercer Island Police Department stated the individual was last seen Friday night around 10:40 p.m. after telling others on board that he needed to use the restroom.

The group was on the lake to observe the annual Seafair air show and hydroplane races. According to police, the teen reportedly made his statement as the vessel prepared to depart the log boom area between Seattle and Mercer Island. The boat was moving at the time and may have been traveling at planning speed.

Authorities noticed the teenager was missing once the boat slowed due to speed restrictions near the Interstate 90 floating bridge. The friends conducted an initial search for approximately five minutes before contacting 911.

Mercer Island authorities have warned that Lake Washington 'can be overwhelming' during Seafair weekend because of the massive boat traffic.

Search efforts, involving multiple marine patrols including the U.S. Coast Guard and Seattle Police Harbor Patrol, commenced immediately. Specialized equipment such as infrared technology, spotlights, and thermal-imaging drones were deployed. The current search area spans about 10 square miles, encompassing the waters around the Lacey V. Murrow Memorial Bridge.

Acting Mercer Island Police Chief Jeff Magnan acknowledged the vagueness of the time and location of the disappearance, stating that the search covered a "pretty big swath of lake." Despite the challenging conditions, officials expressed hope that the teen may have reached another boat or the shore.

The initial search was suspended early Saturday morning due to darkness and operational considerations, resuming later in the day without success. Further suspension occurred due to Federal Aviation Administration restrictions associated with the Seafair event, which features an air show by the U.S. Navy Blue Angels.

Magnan advised boaters to exercise extreme caution during Seafair weekend, noting the increased congestion on the lake and the presence of inexperienced boaters. Investigators plan to obtain and analyze cell phone records to retrace the vessel's path.