Location
The boat landing is at 629W 1593S at the northern tip of Thanatos, and it is the island's one and only port. The Island becomes accessible once you have discussed its location with the Panarii historian Gunther Willhelm. You have to arrive either by purchasing a boat at the Black Root shipyard, or acquiring one from Stringy Pete, or by by winning back Captain Edward Teach's ship. The landing itself is marked on your map once you dock and move on to your next destination.
Area
Point A is the actual docking site.
Point 1 is a barrel where you'll find a journal from a previous adventurer. Reading the journal will give you the locations of the Village of the Ashlag Tribe and the Thanatos Land Bridge.