Whakamoonie swimming hole is listed under gyms in Kingsley Heights, Upper Hutt, with a Google rating of 4.8. By its name it is a natural swimming spot rather than a gym.
Natural swimming holes are free and beautiful, but they need more care than a pool. Water is cold even on warm days, depth and currents change after rain, and there are no lifeguards, so regulars check the weather and river levels first, never swim alone, and keep children within arm's reach. Avoid jumping in until you have checked how deep it is and what is underneath, and wear shoes with grip, since rocks are slippery. Early mornings are quieter, and a towel, water and a spare layer make the day more comfortable. Take your rubbish home and respect any signs about access.
For people in Kingsley Heights and around Upper Hutt, Whakamoonie swimming hole is a very well-rated local spot for a cool dip.