It was the World Cup sovereign Näslund's first Olympic gold in his career.
After the start, Smith was behind Näslund and looked to be able to challenge, but in the end Näslund pulled away and was able to have a perfect day when she won everything.
Behind Näslund it was close and the jury examined whether there had been any breaches of the rules in the heat over silver and bronze.
Näslund was the fastest of all in the qualifiers early in the morning Swedish time.
She then won her quarterfinals, quarterfinals and semifinals, this after taking the start and then staying away.
Alexandra Enebo led her quarterfinal but fell over after a close incident and was four in goal.