Using CS-corrected transmission electron microscopy, we demonstrate the atomic details of a topological vortex-like domain pattern in multiferroic hexagonal manganite YMnO3. The domain configuration shown here is confirmed to be different from a real vortex. The vortex-related issue is discussed and understanding of the vortex-like domain pattern is improved. Moreover, atomic configurations of the interlocked domain walls are revealed with the help of atomistic simulation and insights into the domain wall structure are obtained. The present study can throw further light on understanding of structure-property relation in multiferroic hexagonal manganites.