The 26-year-old Rotorua woman was part of a group of three kayaking the lower Kaituna River, downstream of the Trout Pool, when she was separated from her companions.
Her companions noticed she was missing when she became separated form her kayak.
The alarm was raised and a number of locals began a search for her, which was carried on until dark with no success.
The Police National Dive Squad had been advised and will be arriving in Rotorua this morning to assist with the search.
Police, LandSAR volunteers, and local residents and friends of the missing woman will also be assisting with the search today.