Eastern Pacific High Sea

Along this reach of the Eastern Pacific High Sea, the Baja California peninsula appears as a distinct barrier between two waters. The landmass separates the open Pacific from the Gulf of California and runs from Mexicali in the north to Cabo San Lucas in the south. Its 1,247-kilometre length is matched by roughly 3,000 kilometres of coastline, including about 65 islands. The peninsula is narrow enough in places to frame contrasting seas within a short overland distance, yet its widest sections give the interior a far greater sense of scale. A vessel following the Pacific side therefore passes an unusually long boundary between desert land and ocean.

Four major desert areas shape the land beyond the shore: the San Felipe, Central Coast, Vizcaíno, and Magdalena Plain deserts. Together with the Gulf and the Colorado River, these dry environments explain why the surrounding ocean has long been a clearer route than the interior. Spanish explorers once imagined the land as an island, but Francisco de Ulloa demonstrated in 1539 that it was a peninsula. His survey gave the Pacific approaches a new geographical meaning and turned the long coastline into a recognizable maritime frontier. The contrast between accurate pilots' knowledge and mistaken printed maps persisted later representations of California.