Along the coast of Pernambuco runs a continuous reef of rock with narrow openings at irregular intervals, forming a barrier against attack from the sea.

Olinda, the capital of the provinces, was built on a hill a short distance inland, having as its port a village known as Povo or the Reciff, lying on a spit of sand between the mouths of the rivers Biberibi and Capibaribi.

There was a passage through the rocky reef northwards about two leagues above Olinda and three others southwards (only one of which, the _Barra_, was navigable for large ships) giving access to a sheet of water of some 18 ft.

in depth between the reef and the spit of sand, and forming a commodious harbour, the Pozo.
The problem before the Dutch commander was a difficult one, for news of the expedition had reached Madrid; and Matthias de Albuquerque, brother of "the proprietor" of Pernambuco, Duarte de Albuquerque, a man of great energy and powers of leadership, had arrived in October to put Olinda and the Reciff into a state of defence.

Two forts strongly garrisoned and armed, San Francisco and San Jorge, defended the entrances through the reef and the neck of the spit of sand; sixteen ships chained together and filled with combustibles barred access to the harbour; and the village of the Reciff was surrounded by entrenchments.