On January 26, 2014, about 1615 Pacific standard time, an experimental amateur built light sport Weinzierl Searey amphibious airplane, N669DT, was substantially damaged during an inadvertent water landing near Stanwood, Washington. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The non-certified pilot and his passenger were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local personal flight which originated from Arlington, Washington about 1500. In a written statement and telephone conversation, the pilot reported to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) that following a local sightseeing flight, he intended on conducting a low pass over Lake Goodwin prior to returning to Arlington. The pilot verified the landing gear was in the retracted position and that glassy water conditions were present before he performed a low pass with no intent to perform a landing. The pilot thought that he was about 3 to 4 feet above the water surface when the airplane suddenly skimmed the water surface for about 3 seconds. The pilot pulled up and the nose immediately went into the water. The pilot stated that water immediately began flowing into the cockpit area. The pilot added that the airplane was partially submerged about 3 to 5 seconds later. The NTSB IIC reviewed postaccident photos taken by a private individual about an hour after the accident occurred. The photos revealed that a majority of the bottom side of the hull was separated. The pilot reported no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.