The stricken M/S Explorer sank off the Antarctic coast in 2007
Countries with ties to Antarctica have adopted US proposals to limit tourism in the region, in a bid to protect the fragile ecosystem of the continent.
Parties to the Antarctic Treaty agreed to limit the size of cruise ships and the number of tourists taken ashore at a meeting in the US city of Baltimore.
Limiting tourism has taken on urgency due to a surge in visits and a number of cruise ship accidents.
Antarctic visits have risen from 6,700 in 1992-93 to over 45,000 last season.
The agreed limits will only become legally binding once ratified by each of the 28 nations who have signed the Antarctic Treaty, launched in Washington 50 years ago.
The restrictions do not set out an enforcement mechanism or penalties, but require member countries to prevent ships with more than 500 passengers from landing in Antarctica and to allow a maximum of 100 passengers on shore at any given time.
Another resolution adopted at the meeting places a mandatory safety code on vessels operating in the region, while a third enhances environmental protection for the entire Antarctic ecosystem.
Two cruise ships ran aground during the 2008-09 season, and officials documented several incidents which carried a risk of major contamination.
The most high-profile accident in the region was the sinking of the M/S Explorer cruise ship in November 2007.
Antarctica is the unique home to several varieties of penguin, an important base for others such as seals, and a vital feeding ground for whales.