The Ferryman and Pendragon Meet
On a mission to rescue some lost souls, Pendragon dove too deep in search of a cave near Keelhaul Fort unfortunately drowning in the process. He appeared on the Ferry of the Damned where The Ferryman takes interest in the Sword of Souls that Pendragon holds and tasks him with finding a Lantern similar to the one he owns.
Pendragon returns to the land of the living and swiftly finds the Lantern. Back aboard the Ferry of the Damned, he dipped the Lantern in the Well of Fates and created a Lantern that could see lost souls on the Sea of Thieves.
Source
Sea of Thieves #2: Champions of Souls