Scientists have found a colony of rare Mediterranean monk seals at an undisclosed location in Greece.
The species is the world's most endangered seal, and one of the most endangered marine mammals - fewer than 600 individuals remain.
Researchers are keeping the location of the colony secret to avoid having the seals disturbed by human visitors.
It is the only place in the region where seals lie on open beaches, rather than hide in coastal caves.
Alexandros Karamanlidis, scientific co-ordinator of the Mom/Hellenic Society for the Study and Protection of the Monk seal, explained that this was the seals' "original behaviour".
"It is human disturbance that has caused the species to retreat to inaccessible caves," he told BBC News.
"So this place is incredibly important - the seals feel so secure that they go out on to open beaches."
The Mom researchers, whose society name is derived from the Latin name of the species, Monachus monachus, have been monitoring and studying monk seals for more than 20 years.
This has not been an easy task when most of the animals now live in areas that are not visible from the water line.
By driving the seals into secluded caves, the scientists say, human activity has also affected the number of seal pups that survive into adulthood.
Dr Karamanlidis explained: "Because of human disturbance, [the seals] give birth in these coastal caves, [meaning that] more pups die during storms."
The number of seal pups born annually in the newly discovered colony on this tiny island is amongst the highest recorded anywhere in the Mediterranean Sea.
The team has placed cameras on the island to study the seals remotely.
The area's popularity with tourists has gradually driven the animals away from other beaches, and the scientists hope to stop the same thing happening on this island.
"It's a small island in the Aegean with nice sandy beaches," Dr Karamanlidis told BBC News.
"So if it remains open to people, the place will get crowded and the seals will start going away again."
More than half of the world's remaining monk seals live in Greece.
The society is now appealing to the Greek government to make the part of the island where the seals live, and its inshore waters, a marine protected area.
"The seals only survive in Greece because we have these isolated islands that people do not have access to," said Dr Karamanlidis.
"So we're trying to make this a place where the seals feel secure."