After going for a swim for about 20 minutes the pair returned to the lakefront and packed up to leave.
Leah said when they got to the car the first thing she noticed was that her handbag was gone.
"I started panicking. We looked all through the car and then started asking people nearby if they had seen anything."
She said the car windows were left slightly down because of the hot weather, but not enough for someone to get their arm through.
One person told them to go to the police, who were unable to take clear prints from the car.
She said police took their details but were realistic about the chances of retrieving the items.
Leah said it was deflating as it took her a long time to save up for most of that stuff.
"My message for others is don't leave your handbag in your car and clean it out so you don't have everything in there."
She said it was also important to make sure your phone had good security so people couldn't access bank accounts and other personal information.
A Rotorua police spokesman, who did not want to be named, urged visitors and locals to keep valuables out of sight in their car and if you don't need them to take them out.
He said some iPhones had apps which could track your phone if it were stolen.
He said stolen items should be reported to police quickly with any of the following helpful details - the time of theft, description of what was taken, value of what was taken, details of car or place it was taken from, location and any serial numbers on the valuables.