Comparison of the kinetic energy of ionised gas and the mechanical energy input by young stars for our best candidate superbubbles (as exhibiting shell-like morphology). Top plot: same comparison of energies as in Fig. 16, superbubbles follow the same trend as the other regions. Colour encodes the age of the youngest association in the superbubble. Bottom plot: distribution of the estimated efficiency of the energy consumption in superbubbles. Its peak is slightly below η = 0.25 that was obtained from the modelling by Sharma et al. (2014) as an asymptotic value for the expanding superbubbles driven by multiple (up to a few hundred) OB stars in normal star-forming galaxies.