A husband and wife ended up in Hamilton's Lake Rotoroa earlier today when a driving lesson in a nearby carpark went awry.
Scott Keelty, who works in a cafe on the lake's edge, said he arrived minutes after the red people-mover crashed about 20m into the lake before it started to sink.
Keelty called 111 as other bystanders jumped in to rescue the couple, who couldn't open the car's doors and couldn't swim.
"It was a couple doing a driving lesson in a carpark facing the lake and she's hit the wrong pedal," Keelty said.
The woman hit the accelerator and the car jumped the curb, plunging into the lake shortly after 12.30pm.
"A couple of bystanders jumped in and swam out and got the lady out first.
"Neither of them could swim so they had to be helped to shore."
Keelty said the couple looked to be in their 30s and the woman was pregnant and in shock.
"She couldn't stand she was pretty shaky."
A tow company was pulling the car out of the lake by about 3pm.
Police were called to the lake, off Rotoroa Dr, at 12.37pm, a spokeswoman said.
Neither of the two people in the car when it crashed appeared to be badly injured, although fire services treated a woman for shock at the scene.
Station officer Blair Kiely said by the time his team arrived both people were already on shore by the lake.
The car was completely underwater, he said.
"When we arrived there was a car already submerged in the lake.
"Both the occupants of the car had already been rescued by passers by ... [they] were the ones who jumped in the water and assisted the people to safety."
Kiely congratulated the bystanders for their help.