Aye, ye must leave behind the Sea of Thieves, and sail through uncharted waters. Ye might be off the edge of the map, but we can still help ye find yer way:

Ye must now dive deep below the map into the Sunken Kingdom! There ye must make yer way through two large siren structures: the Spire and the Citadel. Sadly, any map markers we could place atop those structures would cease to hold any meaning once ye be deep inside. Happily, there be better ways to share the sirens' secrets:

Aye, ye must go beyond the Sea of Thieves! Yer map table may be blank, but if ye want to find Jack, ye must think like Jack. Pull out Jack's compass! Jack's compass will tell ye more than any map table! Then again, me hearties, we might tell ye more than any compass:

A shadow haunts the northern reaches of the map: The Coral Fortress! Ah, but there is nothing worth marking on the outside of that fortress—for ye must venture deep into its heart! Aye, but ye need not go in alone:

Just below Davy Jones' tentacles, a Spire will emerge. At the opportune moment, ye must climb that Spire—and there be journals along the way. Ah, but journal markers are less than helpful. After all, it's not very helpful to represent vertically-staggered journals on a horizontal map—particularly to pirates who are climbing a spiral path. It's all just rather dizzying. Don't worry, me hearties. These should clear it all up: