Blowhole may refer to: Blowhole (biology), the hole at the top of a whale or other cetacean's head, homologous with a nostril Blowhole (geology), a hole at the inland end of a sea cave through which waves funnel up and out Blowhole (metallurgy), an internal hole or defect in a cast metal product. Glassblowing. The hole in glassblowing that allow metal/crystal glassblower to insert a tube and force compress air into the metal blob to make a fundamental sphere shape to work with. Japanese tea… (More on Blowhole)