In which the Nautilus navigates the labyrinth of Arabian waters, revealing the wonders of the Red Sea and its peculiar marine life, whilst the narrator and his companions wrestle with the mysteries of their captain’s secret course and the confines of their underwater voyage. Amidst reflections on ancient histories and contemporary marvels, Captain Nemo confides in the professor a remarkable, hidden tunnel beneath the Isthmus of Suez, a natural passage between seas known only to him and exploited by his ingenious vessel.