Oasis

Oasis is a unique settlement in the northern Capital Wasteland in 2277, to the northwest of clifftop shacks.

Background
What is known as the Oasis was once just one of many mines scattered across the landscape of the United States. The extensive network of caves beneath it was used as an impromptu shelter by the inhabitants of a nearby mining town from the bombs. As the time passed, the sheltered rocky vale was stripped of mining equipment and other installations, with only a handful of artifacts surviving to the 23rd century.

Sheltered by the rock formations in the northern Capital Wasteland, it gained a new lease on life in the 2240s or 50s when Harold found himself overwhelmed by Bob in his travels and laid down roots in this area in what the Treeminders call the Harvest Month (when Bob's seed pods ripen and disperse their seeds, resulting in the creation of new trees, grass, and plants).

With Harold's mutation progressing further he became the unwilling heart of an oasis in the desolate wastelands. Around 2257, a small cult formed under Birch, dedicated to the worship of Harold. Birch saw in Harold, not an unfortunate mutant condemned to live out his life as a tree, never again to resume his wasteland travels, but a god. The cult, the Treeminders, were to be his last line of defense.

The Treeminders shun technology in favor of nature, blaming technological progress for all human misery. The control over the cult, exercised by Tree Father and Leaf Mother (Birch and Laurel), with an equal say in its affairs. As the Oasis grew and nature once again reappeared in the wasteland, the cult confronted the hostility of the wasteland. Although they disdained technology, the Treeminders continued to use firearms, to remain on equal footing with their enemies. Only select outsiders were permitted to live long enough to enter the Oasis, though it was rare. Most are turned away, some are killed when they try to gain entry by force, and others are shot on sight, like raiders.

The Lone Wanderer in 2277 is the first one in years to visit the vale. The Oasis is one of the most fertile places in the wasteland, filled with lush vegetation, trees and even birds and squirrels living within the sheltered forest. No other place in the Capital Wasteland is so teeming with life, although there are locations far from the Capital Wasteland, including Zion Canyon and Jacobstown, that have comparable amounts of plant and animal life.

Layout
The Oasis is located inside a large rock formation in the north of the wasteland. The gate to enter it is accessed via a narrow passage in its western face.

The Grove
The Grove is a small part of Oasis that is surrounded on all sides by trees and cliffs. This area can only be accessed after the Lone Wanderer has taken part in the ritual. It is entered via a wooden gate that comes from the pavilion after it has been unlocked. In the middle, the talking tree, uniting Harold and Herbert/Bob, can be found. To the southeast, a small radioactive pond can be found. If the Lone Wanderer dives in the pond, an Easy locked hidden underwater door can be seen, which leads to the damp cave.

The Caves
The damp cave is a cave that connects the Grove with the sunken chambers. It is accessed via an Easy locked underwater door from a pond in the grove. Inside there is a small contaminated lake (5 rads/sec) with a few level-dependent mirelurks. There are several junk items floating on the water of the small lake and on the bottom of the small lake. Several skeletons can be found underwater.

Oasis

 * Maple's garb reward for completing the Oasis quest in the favor of Birch.
 * Poplar's hood and Linden's Outcast power armor both rewards for completing the Oasis quest in the favor of Laurel.

Sunken chambers

 * D.C. Journal of Internal Medicine nearby an orange glowing hole in the wall (inside a wooden box with the baseball glove).
 * One pre-War book, on the trunk next to the table.
 * One Stealth Boy, on the table between some chems.
 * At the bottom of the northern pond, one mini nuke.
 * Past the northern pond, at an intersection marked by green glowing fungi, a Stealth Boy.

Damp cave

 * On land, continuing around the right side of cave, one will find a Nuka-Cola Quantum.

Related quests

 * Oasis

Appearances
Oasis appears only in Fallout 3.

Behind the scenes
The GECK editor suggests Oasis was once part of the wasteland rather than separate world space. There's an inaccessible door where Oasis is located in the wasteland called "OasisDoorFromWastelandToHarold."

Bugs
It is possible that certain dialogue options will disappear after completing the main Oasis quest, making it impossible to obtain your reward. There is no known reason for this, but it may have something to do with certain dialogue choices made prior to completion of the quest.