Merfolk's Lullaby

This is a weird place. It looks like someone used powder kegs to blow their way down into whatever lies below this island. Maybe they managed it somehow, maybe not. Either way, the tunnel they left behind collapsed a long time ago. There has to be another way down. Ancient civilisations love putting secret passages in stuff. It’s a well-known fact! Ask anyone. Whatever it takes, I’m going to get down there. I want to see every last inch of this place before I leave!