Best Group Tours for Solo Travelers (35-45)

I’m planning a trip to Costa Rica and would love to join a small group tour. I’m 39 (turning 40 this year) and from Switzerland. I’ve been traveling solo since I was 21, mostly staying in hostels, so I’m very comfortable traveling independently and sharing rooms. That said, for this trip I’d really enjoy the social aspect of being part of a group.

In the past, I traveled with G Adventures to Vietnam and Cambodia. I chose their Classic tour because I felt I might be “too old” for the 18-to-30-somethings option. I had an amazing time and met some wonderful people, but most of the group were 55+ and retired. While that was absolutely fine, this time I’d prefer to travel with people closer to my own age.

I’m looking for something "active" (not to physiqually demanding) and adventurous, culture and nautre, but not a large coach-style “bus tour.” Ideally, a small group with travelers in their mid-30s to mid-40s. I realize many people in this age range often travel with partners or families, so it seems a bit harder to find the right fit.

If anyone has recommendations for tour companies or specific trips that tend to attract solo travelers 35+, I’d really appreciate your advice.

Thank you in advance! 😊