Kayaks are rolling over as the kids inside desperately trying to hang on for the full rotation.
Nearby, other kids are being capsized out of their small yacht and next to them, surf lifesavers are rescuing a succession of children.
No, it's not a disastrous day at the beach, its Tauranga's annual Water Safety Community Day, and volunteers are taking local kids through a variety of water safety skills.
The event was organised by Tauranga Swim School owner Andrea Sinden.
In its second year, it was held in the pool at Toi Ohomai Institute of Technology today , with around 100 people taking part.
Sinden said the number of preventable drownings in the Bay of Plenty was "huge" and learning water safety skills could save lives, especially with summer coming up.
According to Water Safety New Zealand, the Bay of Plenty had 13 preventable drownings in 2018 - the second-highest rate in New Zealand.
Staff and volunteers from the swim school, Surf Lifesaving New Zealand, Tauranga Young Mariners and Waimarino Education Trust (Waimarino Adventure Park) were on hand to help with the demonstrations.
The top tip from those volunteers to anyone in trouble in the water was to stay calm.
Parent Nikki Polomko, a Welcome Bay mum of four including triplet nine-year-old boys, said water safety was one of the most "essential" skills for Kiwi kids.
"They do teach it at school, but not like we were taught."