Constructed using light steel nets, indicator nets were often anchored at various depths to the sea bed around Allied naval bases during both world wars. They were intended to entangle U-boat traffic of the enemy, even though the submarines often managed to disentangle themselves and escape before being blown up by depth charges. Predominantly deployed by the Royal Navy as a means of discouraging enemy submarines from entering Allied waters, indicator nets were used extensively during the war. Individual nets were sometimes as much as 100 metres (330 ft) in length.