30 Days of Night: Dark Days

A year after the Alaskan town of Barrow's population was decimated by vampires during its annual month-long polar night, Stella Oleson (Kiele Sanchez) travels the world trying to convince others that vampires exist. She is fully aware of the risk to the life that her work could bring, but does not care due to her grief over the death of her husband Eben.
Following instructions from a mysterious individual named Dane, she travels to Los Angeles to give a lecture on the existence of vampires. Aware that vampires attend when she speaks, she activates overhead ultraviolet lamps that incinerate several of the vampires in the audience in front of the humans. She is quickly arrested and harassed by Agent Norris who she learns is one of the human followers of the vampires, placed to keep their activities covered up. After her release from custody, she returns to her hotel to find Paul (Rhys Coiro), Amber (Diora Baird) and Todd (Harold Perrineau), sent by Dane to recruit her to hunt the vampire queen Lilith. As Lilith is responsible for the vampires' every move and for keeping them hidden, the hunters are convinced that once she is eliminated, the vampires will fall into dormancy. When Stella is told Lilith was responsible for the incident at Barrow, she agrees to meet Dane (Ben Cotton) and is shocked to discover that he too is a vampire. Due to a superficially inflicted wound, he has maintained a grasp of humanity, only drinking blood from packaged hospital stocks he keeps. Stella is hesitant to join a plan to attack a vampire nest, but Paul eventually convinces her, telling of his daughter's death by vampire and his accusations of vampire involvement resulting in a divorce with his wife.
The following day, the four hunters enter a vampire nest and are ambushed by a group of them. During their attempt to flee, Todd is bitten. After the four lock themselves in a cellar room, Todd turns into a vampire. When Paul hesitates to act against his friend, Stella manages to kill Todd by smashing in his head with a cinder block. They decide to wait for night when the vampires go to feed in order to make their escape. After night falls, Dane comes and frees them. On their way out they capture a vampire and interrogate him with the ultraviolet lamps, eventually following him back to another nest. They invade the nest and rescue Jennifer, a captive used as a feeding station. Jennifer's knowledge of Lilith's lair being aboard a ship in the bay allows the hunters to plan an attack on Lilith directly. Returning to Dane's place, Stella and Paul become intimate.
Meanwhile, Lilith (Mia Kirshner) decides that Agent Norris should prove his worth to become a vampire (in order to cure the cancer he has been suffering from). He bites the neck of a captive girl, Stacey (Katharine Isabelle), drinking her blood until dead. Satisfied, Lilith turns him to hunt Stella and the others.
Norris kills Dane and the others flee with Jennifer to a boat yard where Jennifer points out the boat that the vampires are set to sail to Alaska in for another 30-day feeding period. After telling Jennifer to leave, the three hunters stow away on the ship where they discover that they can be resurrected after death if they are fed human blood. At gunpoint, they confront the human captain who says he is cooperating because the vampires had threatened his family. Amber is suddenly pulled away from behind, causing her gun to fire and kill the captain. Stella and Paul are too late to save her from being eaten and are quickly captured by Norris and Lilith who orders that they be bled dry. Stella manages to free herself when they are alone with Norris and kills him, but they are subsequently attacked by Lilith when attempting to sabotage the ship and Paul is killed. After being outmatched in hand-to-hand combat, Stella hides from Lilith and when the queen comes looking for her, Stella emerges from her tub of blood and manages to decapitate her. The other vampires appear, but seeing that she killed Lilith, they quietly stand aside and let her pass without a fight, and she returns to Barrow.
Stella digs up Eben's grave and recovers his body to feed him her own blood. It appears not to work and she lies down slowly dying from blood loss. After a time, she sees Eben has returned to his former health and she stands to greet him with a hug. As they embrace, Eben pulls back her shoulder and his sharp teeth come down on her neck before the screen goes dark.

Question: What do the hunters enter?
Answer: Vampire nest.