Traditional third space endoscopy has involved per-oral endoscopic myotomy (POEM) and endoscopic submucosal dissection, but as the field continues to develop, new emerging indications are gaining attention. This chapter will explore the recent advancements and innovations in the field of third space endoscopy. The traditional principles of POEM and ESD have been applied to offer a potentially minimally invasive solution to traditionally difficult to manage problems. Starting in the esophagus, we will explore the use of esophageal POEM (EPOEM) in the management of esophageal diverticula and post fundoplication dysphagia. Moving into the stomach, we will discuss the use of modified gastric POEM (GPOEM) for post-sleeve gastrectomy stricture and as a bariatric procedure. Lastly, in the colon we will examine the use of per-rectal/per-anal endoscopic myotomy (PREM/PAEM) for Hirschsprung disease.