On November 15, 2021, about 0745 central standard time, a Beech A36TC airplane, N1805D, sustained substantial damage when it was involved in an accident near Aransas County Airport (RKP), Rockport, Texas. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, before departure, the airplane contained a total of 70 gallons of fuel: 20 gallons in each wing tip tank (40 gallons) and about 15 gallons in each main tank (30 gallons). The pilot estimated that the cross-country flight to RKP would take about 45 minutes. Shortly after departure, the pilot switched the fuel selector from a main tank to the left tip tank. About 20 minutes into the flight, the pilot noticed “a trail of fuel being sucked out of both the left and right main [tank] gas caps.” The pilot decided to continue with the flight because, at that time, the airplane was about halfway to RKP and the weather was favorable. About 30 miles from RKP, the pilot switched to the left main fuel tank to prepare for a visual approach and landing. When the airplane was at an altitude of 1,200 ft and was about 4 miles from the runway, the engine “sputtered a couple of times and quit completely.” The pilot switched to the right main fuel tank, which indicated 1/2 fuel, and attempted an engine restart that was unsuccessful. The pilot switched back to the left main fuel tank, which also indicated 1/2 fuel. The pilot realized that the airplane was not going to make it to the runway, so he ditched the airplane into Copano Bay, 1.5 miles short of RKP. The airplane impacted the water and came to rest upright. Postaccident examination showed that the airplane sustained substantial damage to the fuselage, both wings, and ailerons. Due to water immersion, the engine could not be functionally tested. The enginedriven fuel pump was removed; residual fuel, consistent with aviation gasoline, drained from the fuel pump, and the drive spline was intact. The magnetos were water damaged and thus were unable to be tested. Mechanical continuity throughout the engine was noted when the propeller was rotated by hand. The fuel selector was found in the left main fuel tank position. Compressed air was applied to the fuel system to verify integrity of the fuel lines and system. The test revealed that air was venting from both the left and right fuel caps; no additional anomalies were noted with the fuel system. Both the left and right fuel caps showed evidence of water corrosion, and the cap O-rings appeared dry and pliable.