Well back during the Cold War the US thought that land-based runways would be a vulnerable target for Soviet attacks, so at one point they tried to make jet-powered seaplane bombers able to carry nukes (leading to the creation of the Martin P6M Seamaster) so that our ability to launch airborne nuclear strikes in the event of war would not be crippled. Said seaplane bombers would need fighter escorts, so Convair made the XF2Y Sea Dart.

The landing gear was made to be a retractable pair of water skis. It was quite innovative, as they could retract back into the "hull" of the plane to retain its watertightness when taxi-ing on the water and to maintain its aerodynamic profile in the air. It also helped keep the jet engines high up and away from seawater spray generated from takeoff and landing, though the process of takeoff and landing also ended up causing severe vibrations for the pilot.