Bookings for lap swimming have been heavy since outdoor pools at Sutherland Leisure Centre reopened last week.
The state government has also allowed lap swimming to resume in indoor pools of at least 25 metres, but has given no indication when learn-to-swim programs will be permitted again.
Sutherland Leisure Centre is one of the few swimming facilities to reopen because of the cost involved.
Heating is the biggest factor, with the water temperature in both the Olympic pool and utility pool maintained at 26C.
The two pools provide a total of 19 lanes, with half-hour time slots for one swimmer per lane allocated between 6am and 2pm.
In the first few days of operation, there was hardly a gap in bookings, which must be made either online or by phone.
The indoor pools at Sutherland have been drained so tiling, jointing and leakage repairs can take place.
The shire's other leisure centre pools remain closed, with pumps at Caringbah being overhauled and the boiler at Engadine being repaired.
"We look forward to welcoming swimmers back to these facilities as soon as it's safe to do so and once works are complete," a council statement said.
Squad swimming has resumed in the 25 metre indoor pool in Cronulla Sports Pavilion.
Cronulla Beach Swim School operator Mark Simpson said there were two sessions, from 5am-8.30am and 3.30pm-9pm.
"We have got five lanes, with one swimmer per lane," he said.
"Normally, they would swim for one and half hours, but they are now doing just 45 minutes.
"It's mostly serious swimmers. We are doing squads, as well as mini-squads with an average age of six to seven."
Mr Simpson said he was getting calls every day from parents inquiring about a resumption of learn-to-swim classes.
"Our answer is, 'We just don't know and we are hoping it will be in Stage 3," he said.
Josh Crowther, who operates Southern Swim School at Kirrawee, said the shutdown was not only hard on businesses, but was affecting children's water safety.
"Like most local businesses we are suffering financially, and especially so because we only opened our doors in November," he said.
"Unfortunately, we also don't qualify for Jobkeeper payments for the majority of our staff as they have been working casually for less than 12 months."
Mr Crowther said the "inevitable decline of children's water safety over the past two months is of great concern".
"If schools, parks and preschools are allowed to operate, then we don't think it will be long until we are allowed to open our doors," he said.
"The industry, in consultation with health experts, has indicated that properly chlorinated environments are not considered high risk.
"We hope that the NSW government shares our view that learning to swim is essential."
