Sargasso Sector is not found on astrographic charts; it is a purely subjective location.
Saying you're in Sargasso Sector signals a dislocation, an alienation from your origins and entanglement in the business of strangers, a sense of being lost or in peril, or both, through having strayed too far, delved too deep, or plain bad luck. Hubris and curiosity lead to Sargasso, but so does following orders, or even drifting. Some say that any jump can lead to Sargasso. And once there, it's difficult to ever really leave. Events in Sargasso Sector are heartbreaking, heroic, petty, pointless, comical, grotesque, transcendant, and may show sophonts at their best and worse. After a wrenching investigation, which revealed far too much, the hero of the classic holo “Sargasso Sector” is told, “Forget it, J'Aykk. It's Sargasso Sector.”