A view of the mainmast on board the Royal Research Ship Discovery (1962) while at sea. The photographer is looking aft, to port and up from the starboard side of the bridge showing the daymark of a red round shape above and below a white diamond shape being displayed from the starboard yard, indicating that she is undertaking surveying or underwater operations. This is Slide 4 of Captain Henry P. Bird's lecture titled "Deep Oceans", about his service as Third Officer on board the Discovery from 15 December 1971 to 16 April 1972. The ship was on a Marine Biological Cruise to the seas off Cape Bojador in Spanish Sahara (now Western Sahara), off the southern tip of Fuerteventura in the Canary Islands, around the Cape Verde Islands and along the West African Shelf off Nouakchott in Mauretania. She sailed from Barry on 4 February and returned on 16 April 1972. The lecture consists of 78 slides.