A Vault built by Vault-Tec explicitly for the Enclave to use as a base and shelter for the nation's top leaders in the event of nuclear war between the USA and another nation. It is now in current times the headquarters of the Enclave Outcast and their main base of operations
The upper level of Vault 98 has 41 rooms, housing the medical and science, security, recreation and education, dining, and washing sections. The security apparatus is considerable, including several holding and permanent cells as well as an armory stocked to Vault-Tec specifications; holding enough weaponry to equip forty security personnel. The upper level also contains the overseer’s office and private quarters, which can be accessed by passing through the security checkpoint in the northern corridor. The upper level contains such amenities as fully functional saunas, a comfortable lounge, showers with hot water, and a large laboratory facility dedicated to medical research and development. The reason for the vault's extensive medical facilities is unknown but they are fully functional and allow vault physicians to develop and test new drugs.
The lower level of Vault 98 has 59 rooms and is home to the living quarters, hydroponic farms for food production, various storage rooms, and a full-size indoor baseball park where the vault's two teams - the Black Bears and Quantum Caps fiercely compete on sports days, also hot dogs and other snacks are sold at two snack stands built into the base ball room. The hydroponic section is equipped with large greenhouses for growing crops and well stocked with seeds and plant samples. The lower level also allows access to the Vault entrance area and back-up generator and computer control rooms.
The engineering floor of Vault 98 has 20 rooms and can be accessed through the lower atrium and sits slightly below the lower level. It contains vital systems like energy generation, water and waste treatment, light and electrical systems control, and the vault incinerator for disposing of refuse and corpses. Vault 98 is powered by a mix of geothermal and nuclear energy provided by a high-tech nuclear generator. Water for cleaning dishes, toilets, and for other non-consumption uses is recycled to conserve water but any drinking water is ground water.