The Papua New Guinea – Solomon Islands Maritime Boundary Treaty is a 1989 treaty in which Papua New Guinea and the Solomon Islands agreed to delimit a maritime boundary between the two states. The agreement was signed on 25 January 1989. The text of the treaty sets out a roughly north–south boundary that is approximately 1,000 nautical miles (1,200 mi; 1,900 km) long and is composed of a single straight-line maritime segment defined by two individual coordinate points. The boundary passes through the Bougainville Strait and the Solomon Sea. The boundary represents a modified equidistant line between Papua New Guinea and the Solomon Islands. The southern coordinate point is the tripoint with Australia.