Wainui River (Bay of Plenty) river. Wainui River (Bay of Plenty) The Wainui River is a river of the Bay of Plenty Region of New Zealand's North Island. It flows north from the Kaimai Range to reach Tauranga Harbour south of Katikati. The catchment has of stream margins. 41% of the catchment remains covered in native bush, but 48% is under pasture and suffers soil erosion. The river includes 3 waterfalls of up to , which have been kayaked. The long former East Coast Main Trunk railway bridge is designated as the limit of the Coastal Marine Area. Downstream, a 3-span bridge takes SH2 over
Wairoa River (Bay of Plenty) as a warm-up. The first major rapid is "Mother's Nightmare" - a long Grade IV rapid finishing with a 2-metre drop. Then follow the few grade III rapids (Helicopter, Double Trouble & Devils Elbow/Washing Machine). Then comes the two Grade V sections, "Top Waterfall" (a small drop into a hole followed by a three-metre drop) and Roller Coaster. After that there is a Grade III rock garden, a Whitewater Slalom gorge and few short grade III rapids leading up to the grade III "Bottom Waterfall" (another two metre drop). Wairoa River (Bay of Plenty) The Wairoa River runs north into