  Optical reference geometry and related concept of inertial forces are
investigated in Kerr-de Sitter spacetimes. Properties of the inertial forces
are summarized and their typical behaviour is illustrated. The intuitive
'Newtonian' application of the forces in the relativistic dynamics is
demonstrated in the case of the test particle circular motion, static
equilibrium positions and perfect fluid toroidal configurations. Features of
the optical geometry are illustrated by the embedding diagrams of its
equatorial plane. The embedding diagrams do not cover whole the stationary
regions of the spacetimes, therefore the limits of embeddability are
established. A shape of the embedding diagrams is related to the behaviour of
the centrifugal force and it is characterized by the number of turning points
of the diagrams. Discussion of the number of embeddable photon circular orbits
is also included and the typical embedding diagrams are constructed. The
Kerr-de Sitter spacetimes are classified according to the properties of the
inertial forces and embedding diagrams.
