Oakland, Calif., may not be on most people's radar for eco-centric cities in the United States, but this coastal gem was named America's fourth greenest city by Popular Science in 2008. It's got the cleanest tap water in the nation, an aggressive composting program, hydrogen-powered public transit and plenty of eco-friendly businesses. It's long been San Francisco's less popular stepsister, but it's coming into its own as a destination for urban eco-travelers.

Home to noted environmental activist Van Jones and his green jobs organization, Green for All , Oakland has lots of green cred. The fact that this city gets 17 percent of its energy from renewable sources, including solar, wind and geothermal energy, landed it the No. 1 spot on SustainLane's list of top 10 U.S. cities for renewable energy . Oakland even has a green homeless shelter complete with a solar-paneled roof — and the city will likely see many more eco-friendly initiatives in the future.

Stay green

Oakland is home to three hotels certified as "green" by the state of California. The Hilton chain of upscale hotels may not have a reputation for eco-friendliness, but the Hilton Oakland Airport hotel's waste management, recycling, energy efficiency and conservation efforts helped it pass a rigorous field survey by the California Green Lodging Program . The same goes for the Courtyard Marriott Oakland Airport , which is Energy Star-certified.

If you'd rather avoid the corporate vibe, the Waterfront Plaza Hotel on Washington Street is a small luxury hotel with 145 deluxe suites — some with fireplaces and balconies. Waterfront Hotel participates in the You Make a Difference program to donate a minimum of $200 per guest room per year to Rebuilding Together Oakland , which rehabilitates the homes of elderly and disabled homeowners.

Travel green

Twenty-three percent of Oakland residents commute by bike or public transit — a number that has no doubt contributed to the city's remarkably clean air and water. You can join them by hopping on one of the city's hydrogen-powered, zero-emissions buses , which have nothing but water vapor coming out of their tailpipes (get the schedules at the ACTransit website ). Oakland is one of the first cities in the world to offer hydrogen-powered public transportation. Public buses also connect to San Francisco, Oakland's Bay Area neighbor, via BART (Bay Area Public Transit).

Hybrid cars are available for rent at Fox Rent-a-Car, or you can see the city a little closer on a bicycle. Bicycles can be rented at Wheels of Justice Cyclery and Oaksterdam Bike Rental.

See green

Oakland's best eco-destinations are its stunning nature preserves and parks. Lake Merritt , a 155-acre tidal lagoon known as "the jewel of Oakland," is the country's only saltwater lake located in a downtown metropolitan area. It's also the nation's oldest wildlife refuge, providing a home to a plethora of wildlife including fish, shrimp, crabs, clams, egrets, herons and many more species. Redwood Regional Park , just a few miles over the ridge from downtown Oakland, offers 1,829 acres of hiking, biking, camping, picnicking and wildlife-watching opportunities.

The Chabot Space and Science Center is another eco-friendly attraction — it was the first museum to be certified as a green business by the Bay Area Green Business Program . This 86,000-square-foot playland operates one of the largest telescopes in the United States for a hands-on view of California's starry skies.

Eat green

Oakland is home to several all-vegetarian or vegan restaurants as well as many more that offer vegetarian menu items; some popular spots include Golden Lotus , New World Vegan and Pizza Plaza . The Mimosa Cafe is another local favorite, with a vegan Sunday brunch menu that includes a tofu scramble, veggie sausage, potato pancakes and avocado omelets. Manzanita on Linden Street also has plenty of healthy fare, including creative California twists on familiar comfort dishes.

For an exotic spin on local ingredients, check out Doña Tomás , a lively Mexican restaurant with a menu that changes seasonally. Located on Telegraph Avenue, Doña Tomás uses local organic produce and sustainably raised meat and has been officially rated as a green business by Alameda County.

Of course, with the city's many urban vegetable gardens and close proximity to hundreds of California farms, many Oakland restaurants follow the 100-mile diet. And for those who plan to pack a picnic lunch, the city's farmers markets won't disappoint.

Tease photo: pbo31

Destination of the Week: Oakland, Calif.
With green hotels, vegan grub and the nation's oldest wildlife refuge, Oaktown stays true to its roots.