According to the Meknčs historian Ibn Zaydan, Mulay Isma'il had an ornamental lake, large enough to sail pleasure boats on, built inside the kasbah. In fact, the 'Alawid prince, a contemporary of Louis XIV, had this lake constructed to guarantee the supply of water, in times of siege or drought, to the palaces and mosques of the town, as well as to the public baths, homes, gardens and the orchards that surrounded the town and provided for its daily fruit and vegetable requirements.
The masterpiece of the complex known as Hri Swani, the Basin of the Norias, Sahrij Swani, is an artificial lake notable for its size (148.75 m by 319 m with a depth of 3.20 m). Three tall crenellated walls that stood around the lake have today been reduced to an isolated section of rampart located on the southwest side towards the Bani Ahmad district and the remains of the base of an enclosure wall more than 2 m thick.