Map

Maps of Black Rock are NOT supposed to exist, but here one seems to be. A vague, cryptic and crudely drawn map but a map nonetheless!
The map depicts three islands, the center island is drawn a rough volcano. It's labeled 'Black Rock' and has the following inscription:

Sutward sail from maiden’s throne,
Set in dragon stone,
Five hundred sirens hear they moan,
Rise to the isle of bone.