Puerto Rico is a semi-autonomous territory of the United States located in the northeastern Caribbean. The territory is composed of an archipelago that includes the main island of Puerto Rico and a number of smaller islands and keys the largest of which are Vieques, Culebra, and Mona. Located in the tropics, Puerto Rico enjoys an average temperature of 28 °C throughout the year. Puerto Rico is mostly mountainous, although there is a coastal plain belt in the north. There are sandy beaches along most of the coast. Puerto Rico has 17 lakes, all man-made and more than 50 rivers, most originating in the Cordillera Central. The most recognizable endemic species and a symbol of Puerto Rican pride is the Coquí, a small frog easily identified by the sound of its call, and from which it gets its name. Christopher Columbus discovered the island of Puerto Rico in 1493 on his second voyage west, and originally named it San Juan Batista in honor of Saint John the Baptist. The name of the island's present day capital, San Juan, honors the name Columbus first gave the island. Populated for centuries by aboriginal peoples, the island was claimed by the Spanish Crown. In 1898, after 400 years of colonial rule that saw the indigenous population nearly exterminated and African slave labor introduced, Puerto Rico was ceded to the US as a result of the Spanish-American War. Nowadays it is a vibrant, modern, bilingual, multicultural society, one that has been molded by Spanish, African, Indian and U.S. influences. Surfing and golf compete with tennis, fishing, kayaking, scuba diving, and horseback riding, not to mention windsurfing and parasailing are for your active time. Throughout the San Juan area, bars, discos and popular restaurants are found on nearly every corner of the city. There is also not-to-be-miss the vibrant nightlife out on the island, including the special charms of resorts in Dorado, Rio Grande, Ponce and Mayagüez.