It was an invisible place, a place so hidden that the early explorers who sailed up the western coast of the North American continent passed the massive bay right by without ever noticing it.

Because nearly dead center in that bay was a large island that blended right in with the actual continent that lie beyond, creating an optical illusion that it was all one seamless landmass.

Early Spanish and English maps detailing the Western coast along what we know today as San Francisco Bay, don't show the Bay as being there at all.

In 1542, Spanish explorer Juan Rodriguez Cabrillo failed to notice the bay more than once as he sailed up and down the coast looking for the fabled Northwest Passage.

That legendary sea route sailors had sought for centuries that would provide them a direct route to Asia.

Cabrillo never found the Northwest Passage, nor did he ever find San Francisco, for that matter.

Terrible storms blocked his path

and would eventually cause him to head home empty-handed.

Although, Cabrillo never made it home either.

During his voyage home, Cabrillo shattered his leg and died of Gang Green, causing his men to finish the journey without him.

In 1579, England's most famous explorer, Sir Francis Drake,

led another expedition up the coast looking for the northwest passage, during which he proved to be a little more accurate in mapping the coast than the Spanish had, although he too still managed to miss the bay as well.

Once again that massive island and a blanket of fog managed to fool even the most seasoned of explorers. Then in 1602 another Spanish explorer named Sebastian Viscano returned home with tales of a magnificent

harbor rich with timber or shipbuilding. Although even these stories would largely be discounted by his own people, who were convinced

nothing was there by all the previous maps that had been drawn before him.

It wouldn't be until the 1770s before the Spanish and other explorers began to finally recognize the error of their ways and acknowledge what had been there all along.

In 1775, a young naval lieutenant named Juan Manuel D. Aiella became the first

to officially sail into the bay and from there he anchored near the largest island at San Francisco Bay's center, the very same

island that had caused so many explorers before him to miss the bay entirely.

He named this island, Day de Los Angeles Angel Island, but it wasn't the only island he found or named in San Francisco Bay during that expedition.

There was one other he found, a smaller rocky slab of land that was difficult to approach even by boat.

This tiny island proved to be mostly inhospitable to any living creature, other than the large number of pelicans who squawked along its shores.

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