  In this work, we use real quaternions and the basic concept of the final
speed of light in an attempt to enhance the standard description of special
relativity. First, we demonstrate that it is possible to introduce a quaternion
time domain where a coordinate point is described by a quaternion time. We show
that the time measurement is a function of the observer location, even for
stationary frames of reference. We introduce a moving observer, which leads to
the traditional Lorentz relation for the time interval. We show that the
present approach can be used in stationary, moving, or rotating frames of
reference, unlike the traditional special relativity, which applies only to the
inertial moving frames. Then, we use the quaternion formulation of space-time
and mass-energy equivalence to extend the quaternion relativity to space, mass,
and energy. We demonstrate that the transition between the particle and
observer reference frames is equivalent to space inversion and can be described
mathematically by quaternion conjugation. On the other hand, physical
measurements are described by the quaternion norm and consequently are
independent of the conjugation, which seems to be the quaternion formulation of
the relativity principle.
