In Antarctica, tour operators police themselves

As a vast expanse belonging to no one nation, Antarctica has unique rules of governance that allow tour operators -- one of the few commercial activities permitted -- to largely police themselves.

The Antarctica Treaty was signed 60 years ago by 12 countries -- it now has 54 signatories -- including the United States and Russia, a notable feat during the Cold War.

It declares the continent is dedicated to science and peace, and freezes any territorial claims.

Other agreements have since been added to the treaty, including the 1991 Madrid Protocol on environmental protection.

Declaring Antarctica a "nature reserve" where the mining of mineral resources is banned, the Protocol says human activities may only be undertaken after environmental impact studies.

The text bans the voluntary introduction of plant and animal species, and the discharge into the sea of oil and gas, waste and untreated water.

It requires visitors to take their rubbish away with them when they leave.

As such, it provides a general framework for tourism.

In the same year, the International Association of Antarctica Tour Operators (IAATO) was founded by seven tour operators to agree on ship scheduling, safety and environmental protection.

It now groups almost all tour operators in the region and is invited to the Antarctic Treaty signatories' annual meetings to discuss developments in tourism and propose new regulations.

Under existing rules, only ships carrying fewer than 500 passengers are allowed to make landings at approved sites and only 100 people allowed ashore at a time.

Visitors must clean their personal effects before going ashore, be accompanied by guides with a ratio of 1:20, must not bring food, leave anything behind or take anything back.

This year, IAATO's 100 or so member companies and organisations voted in favour of measures aimed at preventing ship collisions with whales, and for additional restrictions on the use of drones.