Nova Scotia's Sable Island, known for its shipwrecks and wild horses, is becoming a national park, which means no drilling on or around it.

The provincial and federal governments signed an agreement Monday that bans drilling for oil or natural gas from the surface out to one nautical mile.

"Sable Island never fails to inspire us. We pledge our commitment to Sable Island by providing it with the highest level of protection," said Peter Kent, the minister in charge of Parks Canada.

Sable Island, about 300 kilometres southeast of Halifax, is 42 kilometres long. It's known as the Graveyard of the Atlantic because it's ringed by 300 years of shipwrecks.

It's home to an estimated 400 wild horses, descendants of animals brought to the island during the late 1700s. It's also the breeding ground for seals and birds, including the rare Ipswich sparrow.

Fewer than 250 people visit the island every year, but that number is expected to jump. Parks Canada is working on a management plan.

Mark Butler, with the Ecology Action Centre, said that's necessary to ensure the island isn't "loved to death." But he's worried the drilling ban doesn't go far enough.

"What it essentially means now is that a company could put a drill rig 1.1 nautical miles from the island and drill horizontally under the island. I think that's still too close," he said.

Government officials said oil companies are voluntarily amending their significant discovery licences to respect the ban.

The process to designate Sable Island a national park began last year with public consultations.

Several groups, including the Ecology Action Centre, urged restrictions on the number of visitors to the island and the infrastructure to accommodate them.

The next steps are to amend the federal National Parks Act and add the drilling restrictions to the offshore accord, as well as amend provincial legislation.