They were on a train Wednesday and found the handbag left on a seat.
"When I opened the bag, the first thing I saw were these wads and wads of bills," a teen, named Bendik, said.
"My first thought was to call police."
The cash ended up totaling to $81,500.
They inspected the bag further and found the passport of the owner, which indicated the man was in his 70s.
The man was expected to pick up his money from police on Thursday.
Authorities are not suspicious about the cash the man was carrying and do not suspect any foul play.
They were unsure of whether or not the teens were rewarded for returning the cash.
Though it seems rare, there have been other recent stories of people returning cash that wasn't theirs.
Last week, a man in Tennessee discovered a bag of cash in a dumpster at a gas station. He took the cash into the store so it could be returned.
"I turned it in to the people, the two guys that work there," Joe Ellis said. "I told them about what happened and I gave them the money and he was counting it out, one of the guys in the store. He said it was, I don't know, almost $4,000."
"That's too much money for me to find and not turn in."