Season
- Season 0 1984-09-24
- Season 1 1983-10-30
- Season 2 1984-05-06
- Season 3 1984-11-04
- Season 4 1985-09-15
- Season 5 1986-10-05
- Season 6 1987-09-20
- Season 7 1988-09-18
- Season 8 1989-10-01
- Season 9 1991-01-06
- Season 10 1991-11-24
- Season 11 1993-01-03
- Season 12 1994-02-20
- Season 13 1994-11-27
- Season 14 1996-01-14
- Season 15 1996-10-06
- Season 16 1997-10-19
- Season 17 1998-10-11
- Season 18 1999-10-03
- Season 19 2000-10-08
- Season 20 2001-10-07
- Season 21 2002-10-13
- Season 22 2003-10-12
- Season 23 2004-10-14
- Season 24 2005-10-19
- Season 25 2006-10-18
- Season 26 2007-04-04
- Season 27 2008-01-04
- Season 28 2008-11-11
- Season 29 2009-10-28
- Season 30 2010-07-08
- Season 31 2011-08-01
- Season 32 2012-07-19
- Season 33 2013-05-17
- Season 34 2014-04-11
- Season 35 2015-02-24
- Season 36 2016-04-14
- Season 37 2017-03-20
- Season 38 2018-03-31
- Season 39 2019-04-07
Season 39 Episode
- Season 13 Mysteries of the Ocean Wanderers
- Season 13 Badlands
- Season 13 Hunters of the Sea Wind
- Season 13 Parrots: Look Who's Talking!
- Season 13 Avenue of the Volcanoes
- Season 13 Ytene: England's Ancient Forest
- Season 13 Gentle Jaws of the Serengeti
- Season 13 Monkey in the Mirror
- Season 13 Ocean Drifters
- Season 13 The Call of Kakadu
- Season 13 The Riddle of the Sands
- Season 13 Jewels of the Caribbean Sea
- Season 13 Survival of the Fittest: a Natural History of Sport
- Season 13 Sulawesi: an Island Bewitched
- Season 13 The Little Creatures of Africa's Hidden World
Natural World - Season 13 Episode 11 The Riddle of the Sands
7.10 60 minutes Documentary on the wildlife found through the four seasons in the estuary of the River Ythan in north-east Scotland, a five-mile stretch of marshes, mud flats and sand banks situated some ten miles north of Aberdeen. The waters of the estuary are home to waders, wildfowl, shellfish, small crustaceans, fish and otters. The estuary is a nature reserve and, since the 1950s, the University of Aberdeen has been running a research project to examine its complex ecosystem.
