A small artificial island was built at the site to house an exploration oil well. After additional exploration, construction of the production island began in the winter of 1999–2000. A standard oil-drilling platform, such as those used in the Gulf of Mexico, was not feasible because of the annual formation of pack ice close to the northern Alaska coast. A stable, year-round artificial island was the only way to provide the permanent structures needed for a production oil well. To protect against the erosive force of masses of ice, the island’s shores were covered in concrete mats that extend 4 feet above the average waterline and 18 feet below it.