Traditionally people traveled on rivers, along the coast, and between islands by canoe. Canoes were of very varied construction, and included large sailing canoes used for coastal and inter-island trade, e.g., hiri and kula. Canoes, often fitted with outboard motors, are still an important mode of transport of both people and goods. Small ships of European design have been imported since the early colonial period for use in local trade; there has also been some local production of small ships. The major ports are at Lae, Port Moresby and Rabaul. Kieta, in North Solomons Province, was a major port until the Bougainville Revolutionary Army forced the closure of the Bougainville Copper Mine in 1989. Because PNG has so few roads, coastal and island shipping is relied upon for the transport of most freight. In 1992 250 ships served 18 major ports and over 400 small ports and landings.