Rosario Seaplane Base is a public-use seaplane base located adjacent to Rosario on Orcas Island in San Juan County, Washington, United States. It is owned by the Rosario Resort.Facilities and aircraftRosario Seaplane Base has two seaplane landing areas: 7/25 is 2,500 by 1,000 feet and 16/34 is 10,000 by 1,000 feet . For the 12-month period ending May 31, 2009, the airport had 2,500 aircraft operations, an average of 208 per month: 84% air taxi and 16% general aviation.Airlines and destinations Kenmore Air (Seattle)