Located on the harbor of Bahía de Todos Santos, Ensenada sheltered explorers, freighters and fishing boats for more than four centuries. Juan Rodríguez Cabrillo, searching for the Strait of Anián (the mythical Northwest Passage), entered the bay in September 1542, encountering a small group of indigenous hunter-gatherers. In 1602 Sebastián Vizcaíno named Ensenada de Todos los Santos after All Saints' Day, November 1. During colonial times the harbor was an occasional refuge for Spanish galleons returning to Acapulco from Manila; the last one sailed through in 1815. Ensenada's first permanent settlement was established in 1804, but it wasn't until 1869, with the discovery of gold at Real del Castillo, 35km (22 miles) inland, that this sleepy backwater grew up. Because Bahía de Todos Santos was the closest harbor, Ensenada boomed with an influx of miners, merchants and hangers-on. In 1882 the city became the capital of Baja territory.

Closure of the mines in the 1880s ended Ensenada's boom, and in 1915 the status of territorial capital was shifted to Mexicali. After the revolution, the city catered to 'sin' industries until the federal government outlawed gambling in the 1930s.

Ensenada locals say that Leon Trotsky lived here for several months in the early 1930s after applying for a passport to the US; when it was denied, he moved to Mexico City.

These days, Ensenada is all about tourism, and it doesn't have to try very hard to attract the tourists. There are several celebrated surfing spots on the north coast of the city - waves can reach more than 18m (60ft) on Isla de Todos. In 2006, Brad Gerlach (the winner of Big XXL that year) surfed a wave of 20.7m (68ft). Ensenada is also a fabulous spot to watch the annual migration of the gray whale from Alaska to Baja California Sur between December and March, and in April and May when they return. The wine harvest season in August has become extremely popular amongst alcohol afficionados.