From here to its outfall in the China Sea the river winds for some 400 m.
Nine or ten miles before reaching its outfall the river enters St Petersburg, and 5 or 6 m.
The southern outfall works of the London main drainage system are at Crossness in the neighbouring lowland called Plumstead Marshes.
The chief river flowing towards the Atlantic is the Bidasoa, which rises near the Puerta de Maya, and after flowing southwards through the valley of Baztan takes a north-easterly course, and for a short distance above its outfall at Fuenterrabia constitutes the frontier between France and Spain (Guipuzcoa); by far the larger portion of Navarre is drained to the Mediterranean through the Ebro, which flows along the western frontier and crosses the extreme south of the province.
There are actually two distinct systems, north and south of the Thames, having separate outfall works on the north and south banks of the river, at Barking and Crossness.
The rivers of the narrow mountainous peninsulas form many rapids and cataracts; as the Tondano, draining the lake of the same name to the north-west coast of Minahassa at Menado; the Rano-i-Apo, flowing over the plateau of Mongondo to the Gulf of Amurang; the Poigar, issuing from a little-known lake of that plateau; the Lombagin, traversing narrow canons; and the river of Boni, which has its outfall in the plain of Gorontalo, near the mouth of the Bolango or Tapa, the latter connected by a canal with the Lake of Limbotto.
At the mouth of the Roding (Barking Creek) are great sewage works, receiving the Northern Outfall sewer from London.