Oasis ( quest ) Oasis is a side quest in " Fallout 3 " . It is also an Xbox 360 , PC achievement , and a PlayStation 3 trophy . Detailed walkthrough . The ritual . When the player approaches Oasis , Tree Father Birch will ask that the player follow him , saying that " He " has summoned them . If agreed to , Birch will unlock the gate to the village and lead the player to an outdoor hut . Birch explains that he is the leader of the Treeminders , and that " He " has summoned the player to the village . Although vague about who or what " He " is and wishing the player character to find out on their own , a Speech check may be passed to discover what " He " is . The Treeminders ask that the player drink a sap in a ritual to purge them of all evil that might be inside , so that " He " may go unharmed . After the ritual , the Lone Wanderer is placed in the Grove , where they meet Harold . Harold reveals his true identity , and begs for mercy ; after being stuck in the same position for decades he is eager for death . The other dwellers of Oasis ask instead to either suppress or expand Harold / Bob ' s fertility . To your left after leaving the Grove , an argument between Tree Father Birch and Leaf Mother Laurel is witnessed . Birch wishes to stop Harold ' s growth with a sap ( the same one used in the ritual ) in order to protect him , and Laurel wishes to apply a liniment that will accelerate it , to spread his influence to the entire wasteland . Both want the player to side with them , leaving the others ' wishes ignored . This leaves three basic choices to go about this quest : Instead of these options , Harold may be burned down with a fire - based weapon such as the Shishkebab or Flamer . If this is done , the player will receive negative Karma , and all of Oasis will become hostile . After the argument . The rest of the Treeminders , who are willing to talk at this point , will express their views on the situation . Your reward is based on what you decide to do to Harold ' s heart and who you speak with before entering the caves . Regardless of what you choose to do to Harold ' s heart , speaking with Sapling Yew beforehand is recommended . If you ask her about her " god , " a speech check will become available allowing you to discover Harold ' s fear . If you pass the speech check ( discovering that Harold is afraid of fire ) but choose not to burn him down to complete the quest , she will give Yew ' s bear charm after completion of the quest . As an alternative , the Child at Heart perk can be employed to guarantee success . Siding with Birch Siding with Laurel Siding with Harold Burning Harold Into the caves . The main entryway to the cave system is in the main Oasis hub area . The player can either pick the lock ( 100 lockpick required ) or ask Branchtender Cypress for the key . Resistance in the Oasis caverns mostly consists of mirelurks , mirelurk hunter s , and mirelurk king s ( depending on player ' s level ) , along with the odd radroach . Notable loot inside the sunken chambers includes a D . C . Journal of Internal Medicine ( in a box by the table , underneath a baseball glove ) , a couple of Stealth Boys , and a single pre - War book . If you need crutches for the railway rifle , there ' s a pair on the bed . There is also a silenced 10mm pistol on the table and two cherry bomb s in a crate . After getting the loot , continue to the next pool of water where there is a mini nuke underwater in the center of the pool and two stimpaks by a skeleton further ahead . In the next chamber straight ahead are two ammunition boxes with missiles and flamer fuel ( flamer fuel in an easy locked box and missiles in an average locked box ) . There is a missile , blood pack , RadAway , purified water , and a stimpak in the northeast of the area lying next to a skeleton . Other than that there is no notable loot except a few empty Nuka - Cola bottle s , tin can s , milk bottle s , and small ruined book s . In order to advance , going underwater is necessary at times , so if it doesn ' t look like there ' s a way through , try checking underwater . Near the end of the sunken chambers , a thumping will be heard . This is the sound of Harold ' s heart . When reached and interacted with , the options mentioned before will present themselves to the player . If the heart is destroyed , then the Barkskin perk will immediately be obtained from being exposed to the radiation . This perk grants an inherent 5 % damage resistance . Aftermath and rewards . A nearby door will lead into another cavern , which will lead back to the grove , where either Birch or Laurel will be waiting depending on the choice made . If the heart was destroyed , Birch will be there , expressing regret over not listening to Harold . If the sap or liniment was applied , Harold may be spoken to , and will have some dialogue about the choice , where he regrets being selfish . At this point , the Treeminders who supported the player ' s decision will supply them with gifts . The Treeminders may also be spoken to after this to get dialogue about said choice . Note that Sapling Yew will give Yew ' s bear charm if the speech check was passed , regardless of the choice made . She is also the only one who will give a reward if the heart is destroyed . The sunken chambers . The sunken chambers are the second cave - system you enter . After entering the sunken chambers , walk until you can turn left , do so , and continue forward until you reach a table . Into the dead center of the irradiated pool water : As you continue the road ( near the skeleton ) : Just as you get towards Harold ' s heart , turn left instead of right ( next to a skeleton ) : The Damp Cave . You can access this cave by a door near Harold ' s heart or southeast of Harold is a cave . The cave is noticeable by a white rock above the water . The door to the entrance is under water and can be opened with the Oasis cave key or a Lockpick skill of at least 25 . You can enter the cave from Harold ' s grove , but it is rather meant to be a quick exit from the rest of the cave system . You cannot proceed from here to the rest of the caves , as there is a high ledge in front of the exit to them . Furthermore , entering from the submerged entrance you will need to swim past a couple of mirelurks to solid ground before you can fight them . Inside the cave there could be mirelurk kings , mirelurk hunter , or standard mirelurk s , dependent on the player ' s current level . When you come back above water the second time , on your left will contain : At the southeast side of the cave ( just straight ahead ) :