The term castle's watery defense refers to the use of water as a natural or man-made barrier to defend a castle or fortress. Synonyms for this term include moat, dry moat, ditch, water ditch, moat trench, water trench, and flooded ditch. These barriers were often lined with walls or palisades, and in some cases, were even stocked with crocodiles or other dangerous creatures to deter attackers. The use of a watery defense was a popular strategy throughout history, and was especially prevalent in medieval Europe. Such defenses not only prevented attackers from entering, but also provided a source of fresh water for the inhabitants of the castle.