New Zealand has agreed to a proposal by the United States for limits on tourism in Antarctica.
Measures to protect the ecosystem of the continent were tabled by US Secretary of State Hillary Clinton at a meeting of signatories to the Antarctic Treaty in Baltimore.
All 28 signatories have agreed to introduce legislation limiting shore visits to no more than 100 people at a time.
Antarctic visitor numbers have risen from 6700 in 1992-93 to more than 45,000 last season.
Another resolution adopted at the meeting places a mandatory safety code on vessels operating in the region. Two cruise ships ran aground during the 2008-09 season.