When I was a kid I remember a story about an island being formed off of some South American country. Big celebration, officials planted a flag, etc. Then a few days later another eruption and it was gone.
No idea if it was true or not but great story.
Probably the emptied magma chamber collapsed.
Sunken Cemetery of Catarman, Philippines.
https://www.atlasobscura.com/places/sunken-cemetery