We explore the tunneling dynamics of strongly correlated bosonic mixtures in a one-dimensional double well. The roles of the inter- and intraspecies interactions and their interplay are investigated using the numerically exact multiconfiguration time-dependent Hartree (MCTDH) method. The dynamics is studied for three initial configurations: complete and partial population imbalance and a species-separated state. Increasing the interspecies interaction leads to a strong increase of the tunneling time period analogous to the quantum self-trapping for condensates. The intraspecies repulsion can suppress or enhance the tunneling period depending on the strength of the interspecies correlations as well as the initial configuration. Completely correlated tunneling between the two species and within the same species as well as mechanisms of species separation and counterflow are revealed. These effects are explained by studying the few-body energy spectra as well as the properties of the contributing stationary states.