In the dry southwestern corner of Puerto Rico are cactus and bunch grass. Puerto Rico has no large wild mammals. The mongoose was brought in to control rats on sugar cane plantations. Iguanas and many small lizards abound, and bats are present. Barracuda, kingfish, mullet, Spanish mackerel, tuna, lobster, and oysters are among the many fish inhabiting coastal waters.
Numerous rivers flow down from the mountains to distinct coastal plains.
The northern rivers are long, rich and tranquil waters in comparison to the southern rivers, and the coast is wet and green. Subterranean streams are abundant, especially toward the northwest. In the southwest, mangroves have created an unique canal system. Puerto Rican rivers are not navigable except near the coast, but they provide electrical power and irrigation. Warm and sunny most of the year.