The Tumarina River is a tributary of the Wairau River that drains the Para wetland. The Tuamarina has its source in the Koromiko area, flowing south through the Para wetland, to the Wairau. About a kilometre north of its confluence with the Wairau, the Tuamarina was the site of the notorious 'Wairau Affray', a confrontation between Māori led by Te Rauparaha, and European settlers led by Arthur Wakefield of the New Zealand Company.
The river catchment is a highly modified environment, with the river rating second to bottom in a survey of natural character of rivers in Marlborough commissioned by the Marlborough District Council. In spite of this, there are a few reminders of the original character of the river, including a titoki tree associated with the Wairau Affray, used by the Māori party to secure their waka. A few stands of kahikatea or swamp pine provide an insight into what the original character of the Tuamarina valley. Most of the hillsides are now planted in Pinus radiata.