Tourists take a cruise in the Scandola Nature Reserve, on the western coast of Corsica.

"It's nature's magical design," says a tourist guide, waxing poetic as he comments on the impressive red cliffs plunging into a turquoise sea at the Scandola nature reserve on France's Corsica island.

"Amazing!" exclaims Irena Snydrova, a Czech tourist visiting the UNESCO World Heritage site with her family, along with groups from Italy, Spain and France.

The Scandola Nature Reserve park is an ecological dream.

Their boat sidles up to the Steps of Paradise, rocks shaped into a stairway some 15 metres (50 feet) long, then glides on to Bad Luck Pass, a former pirates' redoubt.

The ages have sculpted the volcanic cliffs into myriad shapes that beguile the visitor, who might imagine a kissing couple here, a horse's head there, Napoleon's two-cornered hat further on...

Tourists wait to board cuise boats in the port of Porto, near Ota, to visit the Scandola Nature Reserve.

'Golden egg'

Since last month, at the urging of the scientific council, boats must keep a distance of at least 250 metres from ospreys' nests during the breeding season.

"It's a good start," Boudouresque says.

Growing numbers of tourists are drawn to Scandola's pristine waters, endangering its fragile ecosystem.

As for the marine park's fish species, Boudouresque says he thinks the thrumming of the tourist boats is scaring them away.

But a crew member, who gave his name only as Diego, blamed groupers for the declining population of corb. "They eat everything," he told AFP.

The reserve is a prime destination for 3 million people who visit Corsica each year.

"It's bizarre for a nature reserve to see all these boats," said Pierre Gilibert, a 65-year-old doctor, who is a regular visitor. "It might be wise to allow access only to professional boats."

Agence France-Presse