Here are widely recognized “top” adventure-travel companies (brief description + what they’re best for). I’ve included reputable sources for major entries — tell me if you want filtering by budget, region, activity (trekking, cycling, expedition cruise, family), or trip length.

1. Intrepid Travel — Small-group, locally led adventure tours around the world. Best for responsible/small‑group land trips (hiking, cultural, multi‑day). (en.wikipedia.org)

2. G Adventures — Small‑group adventure tours with a strong sustainable / social‑enterprise focus; partners with National Geographic on some Journeys. Best for flexible, value‑focused small‑group trips. (en.wikipedia.org)

3. Exodus Adventure Travels (Exodus) — Longstanding specialist in active small‑group trips (hiking, cycling, wildlife, polar, cultural). Best for trekking, cycling and guided active itineraries worldwide. (exodustravels.com)

4. Lindblad Expeditions / National Geographic Expeditions — Expert-led expedition cruises and land programs with a strong science/conservation partnership (National Geographic). Best for wildlife/expedition cruises (Galápagos, Antarctica) and educational trips. (en.wikipedia.org)

5. Hurtigruten Expeditions — Large specialist in small‑ship expedition cruising (Arctic, Antarctica, Galápagos, remote coasts) with a focus on exploration and sustainability. Best for polar and remote small‑ship voyages. (press.hurtigruten.com)

6. Abercrombie & Kent (A&K) — Luxury expedition and safari operator offering high‑end guided adventures and private journeys. Best for luxury safaris, tailor‑made experiential travel. (thetimes.co.uk)

7. Wilderness Travel — Longstanding operator of small‑group active adventures worldwide (treks, safaris, cultural journeys). Best for classic adventure itineraries with experienced guides (mountain treks, remote regions).

8. Backroads — Leader in active‑travel (biking, walking, multisport) with supported routes and high service levels. Best for cycling and walking vacations with logistics handled.

9. Adventure Life — Custom and small‑group itineraries focused on Latin America and polar regions (Galápagos, Patagonia, Antarctica). Best for tailor‑made active & wildlife trips in the Americas and polar zones.

10. REI Adventures — (REI’s guided‑trips brand) known for outdoor/active trips and strong emphasis on skills and safety; note changes to REI’s Experiences/Adventures business reported in 2025. Best for U.S. outdoor and active trips (when available). (en.wikipedia.org)

Notes and tips

• “Best” company depends on activity (trekking vs. expedition cruise vs. cycling), budget, group size, and how much comfort or luxury you want.
• Many top operators emphasize sustainability and local guides; if that’s important, check each operator’s current policies and certifications before booking. (I cited sustainability‑focused operators above.) (en.wikipedia.org)

If you want, I can:

• Narrow this to “best for polar/Antarctic,” “best budget adventure operators,” or “best family adventure companies.”
• Compare 3 operators for a specific region or activity (itinerary styles, average group size, price range, level of comfort).