Using helicopters and boats, Spanish police officers and coast guard sailors searched Friday for seven people whose boat capsized as they attempted to enter Europe illegally from the Canary Islands, police said. The crew of a fishing boat alerted authorities Thursday after they spotted a capsized vessel in deep waters far from the land, said a police spokeswoman in Las Palmas, capital of the Canary Islands. Twenty-nine migrants, all from sub-Saharan African, were pulled from the water by rescuers, she said. Although the capsized boat had no manifest, many of those saved told authorities that 36 people were aboard the boat when it set out. But a Madrid newspaper, El Pais, reported Friday that hopes of finding the seven missing were slim because the boat capsized so far from the coast in Atlantic Ocean waters as deep as 1,500 meters (4,921 feet). During the summer months, thousands of Africans attempt to enter Spain illegally by sea, risking their lives either by crossing the perilous Strait of Gibraltar to southern Spain or by sailing northwest from the Canary Islands out in the Atlantic. Many are caught and repatriated while thousands of others manage to slip through. A Moroccan migrant workers' association, ATIME, says some 4,000 would-be migrants have drowned in the past five years while trying to make such trips.