Fallout 3 Walkthrough: The Oasis
The Oasis is one of the hardest spots to find in Fallout 3, but I have all of the answers inside. If you're having trouble finding it or completing the associated quest, then just take a look.
Finding the Fallout 3 Oasis
Actually finding the Oasis is one of the hardest parts of the quest. It's at the top border of the map, roughly in the middle. There are a few ways to get a marker for it through random encounters, but even a marker won't help much.
The trick is to look for a large curving trail that starts near the top middle of the map and curves to the right side. This is the best map-based landmark to find the Oasis. Follow this path until you reach a large rocky area. The most noticeable landmark is an intact white train engine marked CMR. Move past the wreck and look for a rope bridge over the ravine. This may be very easy to find, since the enclave will establish a listening post there after the appropriate point in the main quest.
Once you cross the bridge, look straight ahead and a little to the right for an extremely narrow path. Follow this short and narrow path until you see the two Oasis guards. Father Birch will ask you to come in and help them.
Understanding the Oasis
Follow Father Birch inside until he takes you to the little pavilion area. Talk to him and agree to partake in the ritual. Once all the Treeminders gather, activate the fountain and drink some sap. Then watch the little sequence. You'll be taken through the gate to see their god after you pass out.
Talk to the tree to find out that it's really Harold. For new players, Harold is one of the two characters to be in all three Fallout games. Dogmeat is the other, if you were curious. It seems that the tree on Harold's head grew so large that he could no longer support it. He collapsed and formed the Oasis around him. He wishes for you to kill him to end his boredom.
Walk out of the grove and approach Father Birch and Mother Laurel. Listen to their argument and talk to each of them. Birch wants you to stop Harold's growth to protect the Oasis. Laurel wants you to accelerate Harold's growth to save the wasteland, even if it endangers the Oasis.
It is important that you talk to the other Treeminders to get their opinions. If you don't, then they may not give you their reward after the quest is over. No matter which path you plan to take, talk to Sapling Yew. Save first though, since you need to pass a speech check or utilize the Child at Heart perk. Ask about Harold, then ask what his fears are to learn about his phobia of fire.
If you plan to kill Harold, then you can actually stop now and just go to the caves. If you plan to stop his growth, then make sure that you talk to Cypress and Maple and learn that they fear the discovery of the Oasis. If you plan to accelerate his growth, then talk to Poplar and Linden. Poplar will tell you that Harold deserves to be known by everyone. Linden will explain that he feels Harold is quite special and that it should be shared.
Once you've done this, you just need to go to the caves or grab a flamethrower. We explain on the next page.
Let it Burn
If you want to be evil, you can torture Harold and burn the entire Oasis to the ground. Just go back to the Grove and attack Harold with any weapon that does flame damage. This will kill Harold and burn down everything. The Treeminders will naturally be quite hostile afterwards, but they aren't armed or armored particularly well.
This is probably the worst outcome. The only reward is a quick finish and some bad karma.
Into the Oasis Caves
All of the other outcomes require you to go into the caves. The gate is locked. If you have 100 points in lockpicking, then feel free to pick it. Otherwise just talk to Cypress to get the key.
The caves are full of leveled mirelurk. They don't attack in large numbers though, even at very high levels. At level 27, I saw 4 normal mirelurk and 3 mirelurk kings. Just remember to use VATS to shoot them in the face. Melee isn't exactly complex at this point.
Move forward to the pool of water in the center of the first chamber. Once you've killed the mirelurks in the area, jump into the water and follow the quest marker. You need to swim under the marked ledge to get to the next area.
Once you've reached the next room, just keep moving forwa rd until you make it to the sunken chamber. There is some fairly good loot along this path. There is an ammunition box and a pre-war book, along with some other bits and pieces by the alcove. The path will quickly lead you to a door to the sunken chambers.
Move toward to the big center area in this chamber. There will be some more mirelurks that you'll have to kill, but again that shouldn't be too tricky for you. Once they're dead, follow the quest marker to the path on the right. You should be able to hear Harold's heart at this point. Keep moving through the chambers until you find it. Step up to the heart and activate it.
You now have to make your choice. You can destroy it, apply the sap to stop his growth, or apply the liniment to accelerate his growth. Make your choice. You may want to examine the rewards and pick your favorite though. I'll cover those in the next section. Once you are done, just follow the markers and backtrack out of the cave. Go to the Grove to see the ending.
Aftermath of the Oasis Quest
No matter which path you take, Sapling Yew will reward you. She only cares that you don't make Harold suffer from his worst fear. Sapling Yew's Charm will give you a permanent +10 to speech. You don't have to keep it in your inventory though. The change should still apply as a perk regardless of whether you keep the teddy bear.
If you decide to kill Harold, then Birch will be upset but generally understand. There are no physical rewards for this specific action, besides Yew's bear. Destroying his heart grants you the Barkskin perk though. This grants a +5% to your damage resistance.
If you stop Harold's growth, then he'll accept his position as a valuable god to the people of the wasteland. Talk to Cypress to receive a missile launcher and a few missiles. Maple will give you a customized robe called Maple's Garb that gives +1 to Agility and +1 to Perception.
If you accelerate Harold's growth, he'll also accept his position as a god. Talk to Poplar to receive Poplar's Hood. This grants +1 to Agility and +10 to Sneak. Talk to Linden to receive Linden's Outcast Power Armor. This custom power armor isn't too bad. It grants +5 to Big Guns, +10% to Rad Resistence, + 1 to Strength, and -1 to Agility.
Evaluation of the Oasis Quest Rewards
Your choice depends a bit on what you want. Most combat-based players will want to kill Harold to gain the Barkskin perk. 5% more damage resistance does come in hand and the other rewards aren't too good for combat lovers.
Stopping his growth isn't a bad option for a stealth character. The missile launcher is fairly worthless, since they are not exactly rare. Maple's Garb is a great outfit for stealth characters though. It has a damage resistance of 12 but is still very light. The bonuses aren't too bad either. Combat-lovers will find the low damage resistance to be too big of a problem though.
Accelerating his growth is also alright for stealth players. Poplar's Hood is quite useful thanks to its +10 to Sneak. The Shady Hat from Moira's quest line is a workable replacement though, so it might be better to go for Maple's Garb. Linden's power armor isn't bad, but it's not great. It's basically just standard outcast power armor with a +5 to Big Guns. By the time a combat player gets to this quest, they'll probably already have something better.