It's not really an island - it's a scuba diving dragon that lives in a really slow moving timewarp, with its butt out the water.
Those people just happen to think that its butt was an island. And didn't realize that there are millions of heavily curried clams on the seafloor.
It has been about 50 years since it last ate, in our time, so it was to be expected that said dragon's butt would explode like this from the curried clams it ate last winter.
This is what I heard on a news interview anyway, where they spoke to Senoir Capitano Acid King, of the fishing boat Hui hui hui, my hands are HUGE!