Ilha do Mosqueiro is an island with a string of beaches just outside Belém. Its main settlement is called Mosqueiro, but often only referred to as Vila.
Buses leave at least every half hour from the terminal at the Vila´s main square, and can be hailed anywhere en route. R$ 3-4, 1 - 1,5 hours. On weekends and holidays there is a daily boat connection.
Don't forget to visit the Praia do Paraiso, a beautiful and typical Amazon River beach!