Carbon Beach is perhaps the most expensive 1 1/2 mile strip of beach in the world, located roughly between the Malibu Pier and just east of Carbon Canyon Road.
The beach is wide, with lots of dry sand, making it particularly pristine and desirable, but public access is fairly limited, there are no public restrooms and dogs are not allowed.
According to the California Coastal Commission, in addition to "Public Access Easement" areas, "the public has the right to use all lands seaward of the ambulatory mean high tide line." Huh? This is no different than other beaches in California.
The access point on the west side of Carbon Beach is called the Zonker Harris* Access Way at 22670 Pacific Coast Highway, between Nobu Malibu (22706 PCH) and 22664 PCH (McDonald's is right across the street).
* Opened in 1983 and named after the hippie Doonesbury character who worships the sun.
You can also park at the Malibu Pier and walk to Carbon Beach. It is about a half mile.
There is also public parking available on the upper floor of 22601 PCH on summer weekends and holidays.
The Carbon Beach West Public Accessway is at 22466 PCH. Funny, Google Maps actually refers to this as Billionaires Beach Public Access.
And there you have it. For a pdf map from the California Coastal Commission showing public beach access at Carbon Canyon, click THIS LINK.