Lambda Paz (also known as Pentarus 3B) was a moon of Pentarus III. Barely class M, its surface was a desert with an average temperature of 55 °Celsius. In 2367, the mining shuttle Nenebek, carrying Captain Jean-Luc Picard and Wesley Crusher to negotiations on Pentarus V, crash landed on Lambda Paz after suffering a thruster failure.

Picard and Crusher, along with shuttle captain Dirgo, sought shelter in a nearby cave that contained a fountain of water. However, the water was protected by a force field and an energy sentry that first injured Picard, and then killed Dirgo when they attempted to access the water. Crusher eventually found a way to deactivate the fountain's defenses using a modified tricorder, sustaining Picard's life long enough for them to be rescued by the USS Enterprise-D. (TNG: "Final Mission"). The existence of the force field around the fountain suggests that this moon was once inhabited by intelligent life with technology comparable to the Federation's, although these natives seem to have since died out or emigrated to a more hospitable place - Wesley Crusher's scan detected no life-forms .