The new Green Hell area is actually quite large, and although you could obviously play the game without the map, it is highly advisable to get it as early as possible to make your walkthrough much easier.
The new DLC begins on a shore near a moored boat. Of course, you won’t start out with the map. So, head east.
Your destination is a half-sunken ship in the southeastern swamps, indicated by the red marker on the map above, or by these coordinates: 36W, 42S. Make your way through the little islands and dive right under the sunken part of the ship.
Swim through the breach in the bottom of the ship, and go into the first level that contains the first chest with:
1x Obsidian Stone 1x Bone
Then, go up. You will quickly encounter the second chest with:
1x Obsidian Bone Blade
Use the crates further up to climb up the deck and enter the cabin with another chest containing:
1x Old Map
