From the publisher's website:

The players are following Columbus by exploring the islands he discovered. Players slowly explore the islands and discover wealth in the form of Gold and fish. As they learn about the land and sea areas of this new land, they position their Caballeros to try to maintain control of the important regions. Castillos give them a measure of protection from others and ships allow them to establish trade and fish for food. Success is measured in the size of land and sea areas they control. Their success is measured twice and in the end these scores are summed and the winner declared.