Aquarobics involved a gruelling hour of work three times a week, each class equivalent to a run of an hour-and-a-half.
"We don't wave noodles in the air - we are there for a reason."
A lot of people recovering from operations or medical issues took part in the classes as it could be much easier to move in water.
She did not take a cent for the classes, no matter how much her pupils tried to convince her, but said she was "spoilt rotten" by her charges.
"It's a lovely community we have here."
Ms Beattie was convinced to get involved with children's swimming lessons after hearing conversations between parents while watching her grandchildren's football games.
"One guy was saying he couldn't afford to pay $150 for four kids' lessons. I thought, 'We can do this'."
Some of her women from aquarobics volunteered to help and together they offered swimming lessons at Omokoroa Campground swimming pool for local children.
Students from Omokoroa Point School and Pahoia School take part.
"We charge them a nominal amount like $10 for 10 lessons and give the school the money."
Ms Beattie went around to local businesses like Payless Plastics and Rebel Sports, which donated gear.
This is now the third year the classes have run.
Ms Beattie's reward is seeing the children she has helped improving their abilities and even competing in school sports. She said she loved seeing the looks on children's faces when they learned something new or achieved something they could not do before.
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