Nature is undoubtedly Manzanillo's best attraction. Its twin bays, Manzanillo and Santiago, where crystal blue waters lap the black and gold volcanic sand, have caught outsiders eyes since Cortes conquered Mexico. During the summer's rainy season, rivers and lagoons swell, forming waterfalls and ponds. White herons and pink flamingos flock to the fertile waters of Laguna de San Pedrito and white butterflies flutter above the flowers in the chamomile fields. Manzanillo ranks as one of Mexico's most important west coast ports, largely because of its rail connections to the interior. Downtown Manzanillo is busy and jam-packed with the bustling seaport and the Archaeological Museum, located just north of downtown at the San Pedrito campus of the University of Colima. The museum displays 5,000 of its more than 18,000 collected artifacts.