The most famous viewpoint over the crater lakes of Sete Cidades is Miradouro da Boca do Inferno. At the back are Lagoa Azul (Blue Lake) and the Lagua Verde (Green Lake). The higher-lying crater lake is Lagoa de Santiago. The crater was caused by a massive eruption that took place around 1440. Sailors who sailed along São Miguel before the colonization, claimed that there was a high mountain on each side. A few years later, with the arrival of the Portuguese, the peak of the western part disappeared.