France kicked off nearly a month of exceptionally large spring tides Saturday, as tourists flocked to coastal areas to witness spectacularly high water levels ahead of the so-called "tide of the century" March 21.

Thousands of people took advantage of the school vacation period to converge on observation spots along the Atlantic coast shortly after 9:00 am (0800 GMT), when Saturday's 117 tidal coefficient (on a scale of 120) reached its high mark.

Among the most popular draws were spots on Brittany's rugged coast, as well as the legendary Mont-Saint-Michel, the Norman hillock that returns to its island state when tides come in.

"It's quite simply fabulous," enthused one woman taking in the scene of surging ocean water with Mont- Saint-Michel's 11th century abbey looming overhead. "It's the Mont as it was in the beginning -- surrounded by water."

She was one of the countless people Saturday who took in the first in nearly a month of remarkably high spring tides in France, whose crescendo comes with tidal coefficients of 118 March 20 and 119 March 21.

That second date will feature what's being touted as "the tide of the century" -- a considerable misnomer, since the ocean rises to that peak level every 18 years.

But the hyperbole in naming the biggest of the approaching spring tides also reflects the enthusiasm people are demonstrating in rushing to the coast to watch the natural spectacle on offer.

"All the hotels on Mont-Saint-Michel are booked full for the month of March, and we're expecting even more people than that," said local merchant Emmanuel Conon, pleased at the boost in business the tidal attraction is expected to produce.

There are additional reasons to celebrate the phenomenon, meantime.

Unlike last year, when large spring tides coincided with enormous ocean swells that battered beaches and cliffs with waves up to 10 metres high along the French coast, no significant flooding or loss of life has been reported thus far.

Despite that auspicious start, however, nearly all localities along France's Atlantic coast remain on alert for possible flooding and storm waves -- and are expected to maintain a high vigilance level to the end of the current spring tide period.