Where to make friends as an adult?

As weve all got adult/working lives to attend to, on occasion i find my (few) friends unavailable when I've got spare time.

I've got my share of hobbies, all achievable solo, but often nice to be able to share with others. Things like some general company on a hike and so on.

I'm not a drinker, or a party person, I much prefer the quieter approach to things. So the usual places such as a pub aren't really an option.

So where does a guy (26m) find further friends?