Second Dawn Bunker

The Second Dawn Bunker, also known as "Becca's Crypt" or the "Level 12 Bunker" was created by a doomsday cult, known as the Second Dawn, over 100 years ago.

According to Gaia, Becca is buried in the bunker.

History
The bunker was built sometime before the Nuclear Apocalypse, by Second Dawn founder, Bill Cadogan.

Throughout the Series
In The Four Horsemen, Thelonious Jaha told Clarke Griffin and Bellamy Blake that there might be a bunker that could save more people. They discover a bunker but realize it is not radiation-proof.

In God Complex, Jaha, Marcus Kane, Monty Green, Indra and Gaia discover another bunker in Polis. They realize the first bunker was a decoy and that people can survive in the Polis bunker.

In Die All, Die Merrily, Clarke and Jaha go against the rules of the conclave, and move most of Skaikru and Niylah into the bunker. The only Skaikru left outside the bunker are Kane and Octavia in Polis; Raven at Becca's Lab; and Monty, Harper, Jasper, and several others at Arkadia.

In The Other Side, the bunker becomes over-populated with approximately 1,564 people.

In The Chosen, Kane and Jaha gas their area of the bunker and sacrifice 364 Sky People in order for there to be enough oxygen and food for everyone else in the bunker as to make room for everyone.

In Praimfaya, Octavia, with Bellamy's and Indra's encouragement, takes the lead of the people within the bunker.

Current Residents
In "Praimfaya", Indra says there are 1,200 inhabitants within the bunker. By "Pandora's Box", there is only 814. After the bunker is opened, they start using the space above ground as well as the bunker. Some the inhabitants also defect to Shallow Valley or are killed.

Current inhabitants of the bunker or surrounding area include:

Unknown
Several people were on Clarke's list or were seen in the bunker at the end of season 4 but have not been seen in season 5. They may have died at some point though their deaths are currently unconfirmed.

Alive
Several former bunker inhabitants are still alive. Murphy and Emori briefly lived within the bunker but left before the culling. Several lived there for six years but defected to Shallow Valley after the bunker was re-opened. Another, Echo, briefly lived there in season 5 before leaving for the valley.

Deceased
Approximately 364 Sky People briefly lived within the bunker before being culled. Among them were:

Notes and Trivia

 * The bunker is big enough to fit about 1,200 people.
 * On a wall, there is a stone sign and flag that reads "From the ashes, we will rise."
 * The Bunker includes supplies like hazmat suits and it has airlocks.
 * According to Jaha, Hardy, and Clarke, there is an underground aquifer with a filtration system, hydroponic farms, oxygen and air scrubbers, and water recyclers, inside the bunker.
 * Raven Reyes, Monty Green, and Harper McIntyre are the only living Sky People in Season 4 that haven't been in the bunker, as Raven was on Becca's Island and Monty and Harper were at Arkadia. Echo was also another living person that has not been to the bunker, despite being outside near the bunker door due to banishment by Octavia.
 * The Grounders' quotes "Blood must have Blood" and "Your fight is over" are originated from the wall décor in the Second Dawn Bunker, and it is just like the Flamekeeper's prayer, "From the ashes, we will rise".
 * In the six years following Praimfaya, Octavia has established total control over the bunker occupants. She forces those, who committed crimes, to compete in gladiator-style fights to survive, in order to gain their freedom.
 * After those six years, there is only 814 people alive in the bunker, which means that at least 386 people died under Octavia's rule.