The present investigation deals with the transition to turbulence and the behaviour of the turbulent flow in spherical gaps. Different initial and steady or time-dependent boundary conditions result in different ways of the transition from laminar to turbulent flows. The dynamical behaviour is investigated by the power spectra of the local wall shear stress at the outer sphere. The structure of the secondary instabilities is observed by flow visualization. The experimentally observed direct transition to turbulence is analysed analytically using similarity considerations.