Some of Holland's most emblematic places -- Hoorn, Edam, Marken, Urk, Stavoren -- lie along the shores of the great lake called the IJsselmeer. Painterly light washes through clouds and luminous mists that seem to merge water and sky. Cyclists test both speed and endurance against its 400km (250-mile) circumference, zipping round in bright Lycra blurs, or plodding along on the dike-top, immersed in wind, rain, or shine. The IJsselmeer (pronounced Eye-sel-meer) has a surface area of around 1,200 sq. km (460 sq. miles), and hosts fleets of traditional boter and sk├╗tsje sailing ships, modern sailboats, powerboats, and canoes. Its waters are an important feeding ground for migrating and resident birds.

Only in Holland could you say, "This used to be a sea." The IJsselmeer actually was once a sea, until the Dutch decided they didn't want it to be one any longer, since it was always threatening to flood Amsterdam and other towns and villages along its low-lying coastline.

For centuries the Dutch have been protecting themselves from encroaching seas, and snatching more land to accommodate their expanding population. One of their most formidable challenges was the Zuiderzee (Southern Sea), an incursion of the North Sea that washed over Frisian dunes to flood vast inland areas between A.D. 200 and 300. Over the centuries, the Zuiderzee continued to expand, and in the 1200s a series of storms drove its waters far inland.

As early as the 1600s, there was talk of driving back the sea and reclaiming the land it covered. Parliament got around to authorizing the project in 1918, and in the 1920s, work was begun. In 1932, in an unparalleled feat of engineering, the North Sea was sealed off, from Noord-Holland to Friesland, by the 30km (19-mile) Afsluitdijk (Enclosing Dike), and the saltwater Zuiderzee became the freshwater IJsselmeer. Since then, a vast area has been pumped dry, converting fishing villages into farming villages, and joining islands to the mainland.