Being similar =/= same...
Not necessarily, that just how it looks like in a flat representation. Compare it to what Antarctica looks like in the Mercator projection:The name 'dark continent' is a little misleading as it implies it's a single continent out there, while in actuality the known world is basically a collective of rocks in a giant pond, surrounded by land (which would be the dark continent).
For reference
Difference being that till now the dark world has been depicted as a giant land mass in which the lake is contained, rather than the lake being a large body of water with more rocks around the known worldNot necessarily, that just how it looks like in a flat representation. Compare it to what Antarctica looks like in the Mercator projection:
However if the Antarctica was somewhat in the middle of the projection, you would get a similar look to the giant pond surrounded by rocks:
what is a mercator thoInterestingly, the Red Line continent in One Piece viewed in Mercator projection would look exactly like the New World in Hunter x Hunter: