Funny to see this article not too long after finishing The Right Stuff - a stellar book about Project Mercury. It's an interesting tidbit and I learned something new.

While it seems that the concept worked, more or less, on one occasion it didn't, and that turned out to be a good thing. In the only Mercury mission which resulted in the capsule sinking - the second one, with Gus Grissom - the capsule settled down at almost 5km deep, but the SOFAR bomb failed to detonate and thus Liberty Bell 7 could have been recovered in 1999.