A planet of the Tau Ceti system with a polar ice cap, beneath which Kathryn Janeway's father, a Starfleet admiral, drowned when she was a young officer.
Tau Ceti Prime is mentioned in the Voyager episode Coda as the place where Kathryn Janeway's father, a Starfleet admiral, lost his life. He drowned under the planet's polar ice, an event that left a lasting mark on his daughter.
In Coda, Janeway is injured in a shuttle crash and finds herself apparently watching her own death and its aftermath. A figure in the likeness of her father appears, speaks of his own death, and urges her to accept that she too has died and to come with him.
Janeway grows suspicious of his insistence. The figure is an alien entity that feeds on the dying and needs her consent. She refuses, and wakes on the planet's surface as the Doctor and Chakotay revive her.