HELDER, The, a fortified seaport town of Holland, at the N. extremity of the province of North Holland, 40 m. N. W. of Amsterdam; pop. in 1871, 17,296. From an obscure fishing village Napoleon I. converted this place into a fortress of the first rank, capable of containing garrison of 10,000 men. Its batteries command at once the entrance to the Zuyder Zee and that of the harbor of the ship canal at Nieuwe Diep. It is connected with Amsterdam by a canal 50 m. long, 125 ft. broad, and 21 ft. deep. The port and coasts are protected from the aggressions of the ocean by dikes, one of which is 6 m. long and 40 ft. broad, and has excellent road on its summit.