Norman is a 53-year-old psychologist who specializes in interviewing plane crash survivors. Years prior, he authored a hypothetical government report outlining protocols for an alien contact team simply to secure grant money. He is surprised to learn the military has used his exact parameters to assemble a real team for a deep-sea investigation. Out of his element underwater, he serves as an observer tasked with monitoring the mental stability of the scientists he originally recommended.

Beth is a zoologist and biochemist invited on the expedition to investigate potential alien biology. Working in a male-dominated scientific field, she frequently encounters sexism and guards her professional reputation fiercely. She maintains a rigid physical fitness routine of running and weightlifting, presenting a tough exterior to protect herself from betrayal or dismissal by her male colleagues.

Harry is a brilliant mathematician and former child prodigy. His exceptional intelligence isolated him during his youth, leaving him with deep-seated anxieties that he masks with extreme logical detachment and occasional arrogance. He treats the impossible physics of the discovered spacecraft as a complex puzzle and enjoys intellectually sparring with his fellow scientists.

Barnes is a retired Navy captain and aeronautical engineer who acts as the military commander for the expedition. He views the spacecraft primarily as a source of advanced technology and potential weaponry. His strict command style and habit of withholding information from the civilian scientists creates friction and paranoia within the underwater habitat.

Ted is an astrophysicist and planetary geologist who is incredibly eager for historical recognition. Recently married and harboring a fear that he is aging out of his prime scientific years, he is aggressively competitive. He constantly attempts to outsmart his younger colleague, Harry, ensuring he receives credit for any major breakthroughs made during the mission.

Arthur is a marine biologist and biochemist originally selected for the expedition team. He suffers from severe seasickness and acute claustrophobia, which ultimately prevents him from making the descent to the underwater habitat with the rest of his colleagues.

Teeny is a Naval engineer stationed aboard Deep Habitat 8. She is responsible for maintaining the power, life support, and atmospheric pressure systems that keep the team alive on the ocean floor. She understands the limits of the habitat's structural integrity.

Tina is the communications officer for Deep Habitat 8. She manages the sonar tracking, external perimeter sensor arrays, and all incoming messages to the command center. She is responsible for rotating the surveillance tapes to the emergency sub.

Jane serves as the unit archivist for the Deep Habitat 8 expedition. She is responsible for documenting the team's findings, setting up video feeds to monitor the alien sphere, and filming external marine life outside the habitat.

Rose is the cook stationed aboard Deep Habitat 8. She provides meals for the civilian scientists and Naval personnel, occasionally offering to cook the newly discovered marine life specimens that appear outside the habitat.

Jerry is a mysterious entity that begins communicating with the crew of Deep Habitat 8 after the sphere opens. Initially speaking in a rigid, robotic manner, Jerry gradually begins expressing humanlike emotions, utilizing casual slang, and displaying a playful but potentially dangerous temperament.