Tuamarina is a small town in Marlborough, New Zealand. State Highway 1 runs through the area. The Tuamarina River joins the Wairau River just south of the settlement. Picton is about 18 km to the north, and Blenheim is about 10 km to the south.

Marlborough District or the Marlborough Region, commonly known simply as Marlborough, is one of the 16 regions of New Zealand, located on the northeast of the South Island. Marlborough is a unitary authority, both a district and a region. Marlborough District Council is based at Blenheim, the largest town. The unitary region has a population of 52,200.