David Attenborough unveils two stunning underwater realms. The flamboyant wildlife of the Red Sea is a stark contrast to the hot muddy Gulf on the other side of Arabia. The Gulf appears at first the ugly sister of the two seas, more famous for sand, oil and war. Look a little deeper though, and nesting green turtles and dancing terns are revealed, with huge whale sharks and gangly cormorants. Both seas have wonderful characters, but the Gulf has hidden riches and, according to the latest science, may even come to the rescue of the spectacular but fragile Red Sea reef. Icon Films co-production with Saudi Aramco & National Geographic Channels.