The rivers of the state include a number of small plateau streams flowing southward to the Sao Francisco River, and several large streams in the eastern part flowing eastward to the Atlantic. The former are the Moxoto, Ema, Pajehu, Terra Nova, Brigida, Boa Vista and Pontai, and are dry channels the greater part of the year.
There is a small, rocky and picturesque island nearer the harbour entrance, which is crowned by a small chapel, dedicated to Nossa Senhora da Boa Viagem.
Casarca dussumieri, differing from Boa chiefly by the rough and strongly-keeled scales, is confined to Round Island near Mauritius.
The true boas comprise some forty species; most of them are American, but the genus Eryx inhabits North Africa, Greece and south-western Asia; the genus Enygrus ranges from New Guinea to the Fiji; Casarea dussumieri is restricted to Round Island, near Mauritius; and two species of Boa and one of Corallus represent this subfamily in Madagascar, while all the other boas live in America, chiefly in tropical parts.
Among its notable public buildings and institutions are the old government palace in Santo Antonio built upon the foundations of the official residence of Prince Maurice of Nassau, with a pretty garden attached; a theatre facing upon the Praga da Republica, dating from the second empire; the palace of the Provincial Assembly in Boa Vista, built in 1860-66, surmounted by a high dome; the municipal palace, or prefecture, on Rua do Imperador, with the public library (Biblioteca Publica) occupying its third floor and containing about 30,000 volumes; the Gymnasium, a large plain building of two floors standing near the legislative palace; the Pedro II.
At the cost of only Boa casualties it had penetrated some 31 m.
One of the commonest species of the genus Boa is the Boa constrictor, which has a wide range from tropical Mexico to Brazil.
The older part of Boa Vista dates from the 17th century.
The three principal parishes of the city are known as Sao Jose do Recife, occupying the sandy peninsula or beach north of the outlet of the united rivers; Santo Antonio, on the island of Antonio Vaz, which was called Mauritia or Mauritzstad during the Dutch occupation; and Boa Vista, on the mainland to the westward, which is the most modern and the most rapidly growing part.