The Abyss

 is a repeatable quest in Fallout Shelter.

Synopsis
''We've all heard rumors of a bottomless Vault, one that is deeper than any others that have been built, but now it seems we may have actually located it! We need to send a recon party to explore the Vault and unlock its deadly secret.''

Objectives
Explore the depth of a bottomless Vault.

Dialogue

 * Sure. I think. I've never been myself, but there *has* to be one, right? (_Conversation_1_NPCEnd_1);
 * You should ask my brother, he used to be the Overseer of this Vault. (_Conversation_1_NPCEnd_2);
 * Look for Deathclaws being too afraid to chase you deeper. (_Conversation_1_NPCEnd_3);
 * Oh, hello, I hadn't seen you there. (_Conversation_1_NPCStart_1);
 * We don't get many visitors down here, with all the critters and whatnot. (_Conversation_1_NPCStart_2);
 * It only gets worse as you go deeper, or so my brother tells me. (_Conversation_1_NPCStart_3);
 * He lives near the bottom, where it's cool and quiet. (_Conversation_1_NPCStart_4);
 * So, there *is* a bottom, then? (_Conversation_1_Team_1);
 * What can you tell us about this place? (_Conversation_1_Team_2);
 * How much further down is your brother's place? (_Conversation_1_Team_3);
 * More or less. Some robots continued to dig a bit more. (_Conversation_2_NPCEnd_1);
 * I like the peace and quiet. It's pretty safe down here, you know? (_Conversation_2_NPCEnd_2);
 * Yup. That was our experiment, to have robots do all of the manual work. (_Conversation_2_NPCEnd_3);
 * Yeah, I haven't seen him in a while. Maybe I'll visit him in the Spring. (_Conversation_2_NPCEnd_4);
 * My eyes must be deceiving me... (_Conversation_2_NPCStart_1);
 * No one has come this deep in decades... (_Conversation_2_NPCStart_2);
 * Even then, very few people ever did. Robots built most of this Vault. (_Conversation_2_NPCStart_3);
 * They malfunctioned, and just kept on digging until they broke down. (_Conversation_2_NPCStart_4);
 * This is the bottom then? (_Conversation_2_Team_1);
 * Why do you stay here? (_Conversation_2_Team_2);
 * So, this is the result of malfunctioning robots?! (_Conversation_2_Team_3);
 * I think your brother misses you. (_Conversation_2_Team_4);