We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

How Many Islands are in the San Francisco Bay?

Mary McMahon
Updated May 17, 2024
Our promise to you
America Explained is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At America Explained, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

There are 18 islands scattered throughout the San Francisco Bay, including uninhabited rocks, protected wildlife refuges, and developed islands with sizable populations. Some of the islands of the San Francisco Bay are quite famous, as is the case with Alcatraz. Many are accessible only by private watercraft such as sailboats, and each has unique features which make it worth visiting, if you can get there.

Many of the islands are set aside as parks and refuges. Angel Island is a state park accessible by ferry from several locations around the bay, and Alcatraz is a national park. Visitors to these islands are welcome year round, although summertime is the peak season for visiting. There are also several wildlife refuges, including the East and West Marin Islands, Brooks Island, and Bair Island. Brooks Island is part of the East Bay Regional Parks District, and hosts migrant birds, wetlands, and walking paths. Bair Island is an extensive wildlife refuge in the South Bay, and is an important part of the Bay Area ecology.

There are also several islands of the San Francisco Bay that are little more than glorified rocky outcroppings. These include Red Rock Island, on the western side of the Richmond Bridge, along with the East and West Sisters, Ballena Bay Island next to Alameda, and Pat Rock. Red Rock Island is also the only privately owned of the islands in the San Francisco Bay, although the fact that it technically lies in three counties makes potential development a challenge.

There are also inhabited islands in the bay. One, Coast Guard Island, is set aside for military use only. The other inhabited islands are all open to the public. Yerba Buena Island lies in the middle of the San Francisco Bay Bridge, and hosts a civilian population along with a small Coast Guard station. Treasure Island, an artificial island attached to Yerba Buena by a causeway, is a former Naval base with civilian housing located at its northern end. Alameda, an island directly off the coast of Oakland, is accessible via a number of causeways and has a sizable collection of examples of Victorian and Queen Anne architecture.

These islands, as can be seen, are quite varied. Many Bay area residents are only capable of naming a handful of the 18 islands, so prepare to impress people with your local knowledge. The varied residences and nature preserves on the islands of San Francisco bay also provide an interesting cross section of Bay area life, both human and animal.

America Explained is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a America Explained researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Discussion Comments
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

Learn more
America Explained, in your inbox

Our latest articles, guides, and more, delivered daily.

America Explained, in your inbox

Our latest articles, guides, and more, delivered daily.