One toddler dead, another critical in separate pool tragedies.

One boy is dead and another is fighting for his life after two separate swimming incidents on Sunday.

A three-year-old boy from Riverwood in Sydney’s south-west died after swimming in a backyard pool.

Police said the boy reportedly got out of the pool and then collapsed.

Emergency services were called to the house on Kentucky Road at about 5.30pm.

The boy was unconscious and they were unable to revive him.

Just an hour later and a few suburbs away another boy was pulled from a backyard pool.

The two-year-old was treated at the scene by ambulance paramedics before a decision was made to airlift the boy to Sydney Childrens’ Hospital at Westmeade.

He is in a critical condition.

The New South Wales government says drowning is a leading cause of death among children under five in the state.

On average 10 children under five drown in backyard swimming pools each year in the state.

The incidents come on the heels of the death of a mother-of-two in Tasmania late last week, who was caught up in strong surf on Thursday afternoon.

Yolande Scheffer reportedly died saving her nine-year-old daughter.

In 2014-15, 271 people drowned in Australia, and 54 per cent percent of those deaths were in swimming pools.

In that period there was a 30 per cent increase in drownings among the zero to four age group.

One in 10 drowning deaths in Australia in the 2014-15 financial year were children under four.

Summer is, unsurprisingly, the peak period for drownings, with one third of all drownings occurring in the Summer months.