A close friend says the 60-year-old woman had diabetes, but it's unknown if that was a factor.
The minivan came from the Marina Green parking lot, jumped a curb, and shot into about 25-feet of water before sinking and getting stuck in mud at the bottom of the bay.
Slowly, the Dodge Grand Caravan emerged from bay, about a hundred feet or so off Marina Green. The body of the lone victim was still inside. And there were still no answers about why she drove off the edge of the park into the water.
"It's horrible, it's very sad," San Francisco resident Cherrie Badolato said. "This is a place of happiness, we're fortunate that the soccer field wasn't loaded."
About 5:15 p.m. Friday, the minivan jumped a curb going about 20 miles an hour and plunged into the bay.
Members of a boating team at the Golden Gate Yacht Club jumped into a motor boat and tried to save the woman as her vehicle quickly sank. One of them recorded dramatic video of the rescue.
"It was going down at the nose, the roof was just submerging when we got to it and before we even slowed down, three of our guys were in the water with tools and they were able to get on the car and started smashing the window, but unfortunately we couldn't get the window to break completely," rescuer Ian Andrew said.
SKY7 HD was overhead as police and fire rescue crews worked for five hours to get the vehicle out of the water. But darkness and the currents made that job too dangerous.
They returned Saturday morning and were able to retrieve the victim and get the minivan out of the water. Contents of the vehicle floated in the bay, including prescription bottles and a disabled placard.
"You can't assume anything until you talk to the next of kin and check the vehicle," SFPD Lt. Toney Chaplin said. "It could have been a mechanical issue, it could have been a medical issue. So we don't want to speculate until we know for sure."
Neighbor Daryl Draper saw the woman and her van Friday.
"She's a nice lady," he said. "You know, I think she's a spiritual lady. I don't know too much about her, but I know she's really friendly and I had no problems with her."
The woman's name has not been officially released by the medical examiner's office, but we've been told some loved ones have been notified about what happened.
Police are asking for any witnesses to come forward that might help explain how this happen.
What to do if your car starts sinking in water:
So how can you save yourself, should the unthinkable happen, and you find yourself trapped in your car underwater? An estimated 400 people die each year because their cars are trapped in water. Most of the victims wait or call 911 expecting help. Safety experts say don't wait: unbuckle your seat-belts, get the window open, and get out of the car before it sinks. And because the back windows on some cars don't roll all the way down, passengers should head through the front ones. An inexpensive window break tool can punch out the glass before water fills the inside of your car. Experts warn the first 30 to 60 seconds are key to trying to get out of the car.