What are some things to do with a 4 year old near San Francisco?

My brother is bringing my nephew over here to visit my parents and I in the San Francisco Bay Area in one month. My nephew hasn't been to see us since he was two years old, and I was trying to think of fun things to do in the Bay Area that the whole family can enjoy. We had plans to take him to the aquarium at Pier 39, to Great America, the Exploratorium, to the nearby parks and the beach, but I was wondering if there were any other kid friendly places I'm missing. We live in the Peninsula, so anything in San Mateo county, San Fransisco county, Santa Clara county, Marin county, and Contra Costa county would be doable. We're not going to be able to do everything, but I don't know what places are meant for little kids, and it would be nice to focus on those.



Also, any tips on projects we could do with a 4 year old when we're spending time at home would be great! Thanks!What are some things to do with a 4 year old near San Francisco?
The Children's museum in San Jose is great for this age.



The Lindsey Wildlife Museum in Walnut Creek was a pleasant visit for us last summer. Lots of wild birds (watching the feeding was fun), smaller, not as crowded.



We found the Oakland Zoo to be plenty for us - it's a bit smaller than the SF zoo, with a small train you can ride.



The Academy of Sciences in Golden Gate Park has an aquarium, planetarium and rain forest all under one roof. This can get pretty crowded (go on a weekday while school is still in session if you can).



Six Flags Marine World is in Vallejo. Amusement park rides, a "marine world" animal park all wrapped into one.What are some things to do with a 4 year old near San Francisco?
In SF proper

Yerba Buena Gardens, green space, carasol, movie and live action performance.

Randall Museum above the city. A kids history, biology museum with a great lawn, with art and some of the best views of the city.

The Zoo as other's have mentioned

The Embarcadero, a wonderful walkway, along the water. Stop by Red's, the Ferry Building, Waterfront Restaurant, or Fog City Diner.

Enjoy the view of Treasure Island to the east.What are some things to do with a 4 year old near San Francisco?
In Golden Gate Park, there is a restored old fashioned carousel with horses that go up and down and music playing.

If he is not from a coast, then the beach is always fascinating. Swanton Berry farms has a you-pick-them strawberry field. They are on the Peninsula on the Coast.



I wouldn't necessarily go to the Exploratorium. At 4, many of the exhibits would be above his head (both physically and mentally)What are some things to do with a 4 year old near San Francisco?
The S.F. zoo is reasonably fun, and is two blocks from the beach.



If he's like most kids, a trip on the cable car and on the streetcar out to the zoo is nearly as much fun as wherever it is you're going.
The SF Zoo is a great place for kids.



Golden Gate Park is awesome for kids as well. They got that big childrens playground there.