Greenpeace would ban diving if they could. I'm sure they would complain about divers fins touching corals, masks being found at the bottom, spearfishing, the pollution from boats, etc. Don't confuse environmentalists with conservationists. A conservationist goes hunting, fishing, diving, but doesn't kill/destroy every animal. A conservationist enjoys the resources around him, he gets on a 4x4 or a snowmobile and takes advantage of the national parks, which were created by Teddy Roosevel who was a hunter, fisher, and a conservationist.
An environmentalist like PETA or Greenpeace thinks that humans are evil. They know nothing about mantaining a forest or an ocean. They think the environment is better when it's left alone. What bull! In California people know that if you don't remove dead trees and give them to the lumber industry, you're more likely to have forrest fires.
As far as I'm concerned, Greenpeace is an anti-diving, anti-freedom organization. And if you don't want to end with a dive tax, you're better off opposing them.