A major objective in proving the Strong Cosmic Censorship Conjecture is to characterize the nature of singularities inside generic black holes. I will present new results on the interiors of spherically symmetric, dynamical black holes, which reveal the existence of two distinct types of singular boundaries: a weakly singular Cauchy horizon and a strongly singular spacelike singularity. Our quantitative analysis uncovers a transition region between these two singularities, wherein the Einstein equations exhibit a novel dynamical regime.