There will be some enemies ahead that aren’t too dangerous, so take care of them and come to the long narrow path with more enemies ahead. Once that has been done, these large stone doors will open up and this path will lead you to the Abyss Watchers boss area if you keep following along. The objective in the swamp is to put out three flames that are located in these chimneys.
This area can be quite nasty, and the swamp is poisonous, so be sure to have some purple moss clump consumables at the ready.
It can be quite a pain getting there, so allow me to walk you through the dreaded poison swamp that surrounds it. Look for the bonfire near Farron Keep Perimeter. The first true farming location in Dark Souls III can be found near the Farron Keep area. Farming souls may be frowned upon in some gaming circles, but let’s be honest - you absolutely need to farm sometimes in order to make it past certain areas and bosses. Doubtlessly, farming locations will be part of this discovery.