Like I just don't understand the scenario here?
Post college, it just feels like online data is the only real option.
But here's some suggestions: bus stops, the park next to a bakery, library if you like books, art classes, sports events, museums, opera, larp if you like costumes, some cafes and cinemas have singles events, boat tours, zoo
I'd advise against clubs, beaches, or sauna if you don't feel confident yet, because those locations are unnecessary difficult.
And basically any place where something predictable happens that you and other people can stop and look at and talk about is easy. Like if you stand next to a construction site, girls who want to talk to you will have an obvious topic to initiate the conversation with.
That said, you want to target the underachievers, not the people who are seriously doing the activities.
I hike. I've met multiple people out there who see it as a way to meet the opposite sex. Oops--every man I've met doing this is in male-dominated groups, every woman I've met doing this is in female-dominated groups. Difficulty levels, not sexism.