An unusually heavy influx of undocumented immigrants, who arrived on the coasts of Spain's Canary Islands over the weekend, has highlighted the ineffectiveness of wire fences and other police measures designed to keep people from sub-Saharan Africa from seeking a better life in Europe. Between Friday and Monday (8 to 12 May), the Civil Guard and local police intercepted and detained more than 500 people who arrived in Spain in canoes and "pateras" (precarious, low-floating wooden boats designed for shallow waters). Most were coming from Mauritania and Morocco.