During the development of the Avro Arrow supersonic interceptor in the 1950’s, 3-meter-long scale models were lobbed to high speed atop solid rockets. The models were shot into Lake Ontario, where they sank and were lost to history. However, it looks like someone is goign to make an effort to find and recover them:

New Search For Avro Arrow Flight Models Lost 60 Years Ago in Lake Ontario Has Begun

I suspect if the models are found, they’ll be found in itty bitty bits. Smacking into water at Mach 1 is rarely good.