The divers were brought in today to help search for the missing 26-year-old man and a 31-year-old woman at the lake at Westlake Reserve in Halswell.
Witnesses told police they saw a man and a woman arguing late yesterday afternoon shortly before the car went into the water about 5.45pm on Tuesday.
The man was reported to have dived several times to get to the submerged car before failing to resurface.
The bodies were found late this morning.
A family friend of the missing couple told Radio New Zealand that the pair lived in Christchurch but were from Fiji and had a six-month-old baby, who was being looked after by family.
He would not confirm what led to the crash, but some media have reported the woman was being given a driving lesson.