[paul m]

Yes, that's why I quoted it; but TRIBES is a commercial, profit-making company and its listings are not comprehensive. They seem to approve, for instance, of flying people into natural areas ....
It's just that I'd like to see something more objective and impartial?
Your site is interesting ...

Originally Posted by tdaspit

Looks to me like the website you provided a link to has your best answer. Responsible travel and ecotourism holidays from Fair Trade Travel company, TRIBES. They list several organizations that rate the environmental friendliness of travel groups. There were several listed.

I'd check into those organizations.