Structures including an edge coupler and a crackstop, as well as methods of forming a structure including an edge coupler and a crackstop. A waveguide core and a crackstop are located over a top surface of a dielectric layer. A communication passageway is either optically coupled or electrically coupled to the waveguide core. The communication passageway, which may include an electric conductor or a buried waveguide core, extends laterally beneath the crackstop.