The main inland waterways total about 18,200 kilometers, 11,000 kilometers of which are navigable by riverboats. A well-developed and important form of transport for both cargo and passengers, inland waterways transport approximately 3.8 million metric tons of freight and more than 5.5 million passengers annually. Main inland waterways are the Magdalena–Cauca River system, which is navigable for 1,500 kilometers; the Atrato, which is navigable for 687 kilometers; the Orinoco system of more than five navigable rivers, which total more than 4,000 kilometers of potential navigation (mainly through Venezuela); and the Amazonas system, which has four main rivers totaling 3,000 navigable kilometers (mainly through Brazil). The government is planning an ambitious program to more fully utilize the main rivers for transport. In addition, the navy's riverine brigade has been patrolling waterways more aggressively in order to establish safer river transport in the more remote areas in the south and east of the country.