A cyclist died in knee-deep water after losing control of her bike in a Hamilton reserve and falling into a creek at the weekend.

Late last night, police were still trying to identify the victim, who is believed to be in her early 30s and of Maori or Pacific Island descent.

Police said the woman struck a fallen tree at the bottom of a winding, steep path in Edgecumbe Park, Whitiora, before plunging down a 4m bank.

Acting Senior Sergeant Pete Whittaker said the woman, who was not wearing a helmet, was likely to have been knocked unconscious before drowning in the Waitawhiriwhiri Stream, which was "only up to his knees".

"She must have been going at a fair whack, and the hill is just so steep. There's skidmarks on the grass where she's failed to veer around the corner, and it looks like the tree has clothes-lined her. It's just tragic."

Mr Whittaker could not confirm when the accident happened, but said the cyclist was likely to have been riding through the reserve alone on Saturday night.

He said anyone walking down the path between Edgecumbe Rd and Charlemont St would have spotted the body.

Two 15-year-olds who were "taking a breather" from their morning church service at Central Baptist Church yesterday found the body head-down in the creek, which runs off the Waikato River. The cyclist's mountain bike lay nearby in the water.

The pastor's wife, Sally Allen, said that by the time the youths discovered the body, there was nothing they could do to help. They alerted their parents, who called for emergency services.

"We'll be praying for the family next Sunday," Ms Allen said.

The paving stones on the path were being repaired, and the cyclist ignored a sign at the top of the hill that said, "Footpath closed".

The woman's body was removed from the creek yesterday afternoon. She had a bob haircut and was dressed in aqua-blue boardshorts and a black T-shirt. She was wearing a tiki around her neck. She wasn't wearing shoes.

Residents who lived around the park said people rarely cycled down the hill from the Charlemont St end because the slope was so steep.

A pathologist will carry out an examination today to determine the cause of death.