https://www.youtube.com/watch?v=6pl1aMVnZyY&t=8m17s

Speeds in excess of Mach 1 were attained in shallow dives with this
aircraft, making it the world's first and only supersonic seaplane to date.
In 1954 a Sea Dart disintegrated in midair over San Diego Bay during a
demonstration for Navy officials and the press, killing Convair the pilot
when he inadvertently exceeded the airframe limitations. The Navy's interest
had waned since the advent of supersonic carrier jets anyway, so the
remaining four were pulled from service and consigned to museums...