In 1994 Alcubierre developed the first warp drive work using the original 3+1 ADM-MTW formalism.Seven years later in 2001 the same original 3+1 ADM-MTW formalism appeared in thefirst part of the second warp drive work developed by Natario. But in 1997 the concept of the Relativistic Geometrical Horizon RGHwas introduced by Hiscock in his work about the Alcubierre warp drive. According to Hiscock if the time component of a given spacetime metric tensor becomes null g_(00)=0 a Horizon similarto the Event Horizon of the Schwarzschild black hole appears. Hiscock computed the Relativistic Geometrical Horizon RGH for the Alcubierre warp drive.We present in this work the RelativisticGeometrical Horizon RGH for the 3D version of the Natario warp drive with both constant and variable speeds.Remember that a real spaceship is a 3D object and a spaceship must accelerate or de-accelerate in order to be accepted as a physical valid model. Due to the presence of three spatial dimensions the g_(00)=0 never appears however in a dimensional reduction from a 3+1 spacetime to a 1+1 spacetime the Relativistic Geometrical Horizon RGH g_(00)=0 appears again.