High tide submerges a narrow causeway leading to Mont Saint-Michel on France’s northern coast. (AP)

It’s called the “tide of the century” — every 18 years, when abnormally high spring tides engulf the English Channel. For a short time on Saturday, thousands of visitors were treated to a rare sight at France’s famed Mont Saint-Michel as the supertide overtook its narrow causeway, transforming the ancient abbey into an island.

“It’s been a long time since we’ve seen Mont Saint-Michel surrounded by the sea,” Wilfred James told the Associated Press. James drove six hours from central France to catch the tide. “I was born in this region and I never saw it like this,” he said. 

A view from the abbey. (Guillaume Souvant/Agence France-Presse via Getty Images)

Generated by Friday’s solar eclipse, the moon’s extra-strong gravitational pull sent tides into the channel “at the speed of a galloping horse,” as the saying goes. The tide peaked on Saturday night at a record 46 feet, as Agence France-Presse reported, but visitors also got to experience the day’s low tide by wading out onto the seabed.

[Related: The beauty of a rare total solar eclipse]

(Pascal Rossignol/Reuters)

The gothic Benedictine abbey was declared a UNESCO World Heritage site in 1979, and attracts 3 million tourists per year.

The last “tide of the century” came on March 10, 1997 — and the next will come on March 3, 2033.