Landscapes are hydrologically complex and sui generis. Yet, surprising simplicity and similarity can emerge when different catchments’ hydrological behaviours are compared. Here I use large-sample datasets to expose hydrological similarities and differences between regions. Based on these patterns, I address diverse questions such as “what affects seasonal and annual water balances?”, “which processes drive flooding?”, “how far do floods extend beyond catchment boundaries?”, and “why is streamflow so much older than storage?”.