A compact city on 42 wooded hills, surrounded by the Pacific Ocean and a vast bay, San Francisco is small enough to walk across or sail around in a couple of hours, which is what locals do just for the exercise.

Visitors, on the other hand, are here to take their time taking in those world-famous views and that salty air. And in what has been called one of the "Top Ten Green Cities" in the U.S., getting around on foot, by bike or kayak, Segway or skateboard is easy, thanks to companies that offer guided tours geared to active people who want to see and touch the "green."

Throughout the city in more than 200 parks and on sandy beaches, in one of the largest urban parks in the world, a sprawling National Recreation Area, and on palm-fringed boulevards that trace the waterfront, America's "Best City for the Outdoors," according to Forbes.com, is open for exploration, every day of the year.

LAND HO!

The most popular guided walk offered by California Nature Tours is called "The Wild Side of Nature," a four-mile stroll along a paved section of the California Coastal Trail, with stops at the Golden Gate Bridge, Golden Gate Park and the Presidio, ending on the Pacific Ocean side of the city on the cliffs at Land's End, and at Ocean Beach. The tour guide and company owner, David Schmidt said, "People are surprised when I tell them the walk is mostly flat or downhill. It starts at the level of the Golden Gate Bridge and finishes at sea level! They also tell me that they never expected wilderness in San Francisco."

An environmental writer with the Environmental Protection Agency, and a fifth-generation San Franciscan and grandson of a 1906 earthquake survivor, Schmidt regales his small tour groups with a steady narration of history and wildlife. He said, "The Presidio's new Coastal Trail segment is just half a mile from the bridge. It traverses an entirely undeveloped side of the Presidio, a rocky, untamed slope covered with wild plants and shrubs, the same native landscape that greeted Spanish sailors in the 1700s and the '49ers who flocked here on their way to the Gold Rush."

Owner/tour guide at Urban Trek USA, Anton Gaddi shepherds his clients around the city on public transportation, including the historic Italian streetcars, and on foot, to such attractions as Marina Green, a breezy greensward on the edge of the bay where joggers jog and kites fly against the backdrop of Alcatraz, the bridge and a row of fanciful vintage mansions. Gaddi said, "From the Marina we head along the bay front to Crissy Field, the former U.S. Army air strip that has been wonderfully restored to dunes and a salt marsh. I tell the story of Major Dana Crissy, one of 46 pilots who participated in the 1919 Transcontinental Reliability and Endurance Test. He died on the first day trying to land, and only nine planes completed the test."

While the Gaddi's groups enjoys watching yachts, freighters and windsurfers ply the bay, he spins tales of the aviation history at Crissy Field, such as the first transcontinental flight, in 1924. and the first nonstop flight to Hawaii.

From here, the Golden Gate Promenade, a wide sidewalk perfect for in-line skates, baby strollers and sightseers, runs east around the waterfront to the beach at Aquatic Park, past Fisherman's Wharf, Pier 39 and dozens of piers to the indoor/outdoor marketplace and wharf at the Ferry Building at the foot of Market Street, and on to AT&T Park, home of the San Francisco Giants.

RIDE A BIKE

A big biking city, San Francisco provides bike spaces in every parking garage, bay ferries all have bike parking and many MUNI buses and trolleys have bike racks. The San Francisco Bike Coalition provides maps of the miles of bike trails in and around the city. For those who are reluctant to pedal off on their own, Bay City Bike has for more than two decades led bikers on city tours. They rent bikes for all ages and abilities, from "comfort" and "performance" bikes to tandems, and kids bikes, along with child seats and trailers. The most popular of the tours is the "Daily Guided Tour" from Fisherman's Wharf to Fort Mason, Crissy Field, the Presidio and Fort Point and across the Golden Gate Bridge. The trip ends with an exciting two-mile downhill ride into the Mediterranean-style village of Sausalito, and a return trip to the city by ferry across the bay.

PADDLE THE BAY

Early mornings and evenings, when sea breezes are calm, are the prime times for paddling a kayak around the waterfront and the bay. Kayaking is a beloved sport among San Franciscans, who are often seen floating in McCovey Cove just outside AT&T Park when a baseball game is underway. Kayaks, surfboards, canoes, inflatable rafts, rowboats and inner tubes are often in evidence, too, vying for position to catch "splash hits" — home run balls — that fly out of the park.

Kayakers unsure about the tidal schedule, which effects changing conditions on the bay, can check the City Kayak website for their guided kayak tours, which are timed to take best advantage of the movement of the tides. From South Beach Harbor, City Kayaks rents boats and leads small groups to Alcatraz and the Golden Gate Bridge and around the yacht harbors, coves and beaches.

TAKE IT IN SEGMENTS

Gliding along at 12 mph, riders on quiet, battery-powered, two-wheeled Segways enjoy the fresh air and the sights of the city while expending minimal physical effort. Used to first-timers, San Francisco Segway Tours conducts short training sessions to get passengers comfortable with the well-balanced, fat-tired machines, and then everyone heads off for narrated jaunts along the waterfront. The "Run for the Palace Route " runs from Fisherman's Wharf west through the Marina District past the yacht harbors, along the Marina Green and around the lake at the Palace of Fine Arts.

ON YOUR OWN

A wide variety of free, guided, narrated walks are given by San Francisco City Guides. For intrepid hikers with strong legs, the Sutro Forest Hike is a steep, long, strenuous walk, taken at an easy pace and rewarded with spectacular views, while the Golden Gate Heights Stairways expedition ambles up and down some of the 300 hidden stairways — some more than a century old — that wind up and down the city's hilly neighborhoods, through forest glades and lush gardens.

At Pier 45 at the Museum of the City of San Francisco, visitors can pick up a free do-it-yourself walking tour map of several routes laid out by the San Francisco Museum and Historical Society. History buffs take the Barbary Coast Trail, which is marked with bronze medallions set in sidewalks. The 3.8-mile route meanders along the Embarcadero and into the city to 20 historic sites, among them the birthplace of the gold rush, the oldest Asian temple in North America, Silver King mansions and the largest collection of historic ships in the United States.

And, for those who cannot walk, bike, Segway or kayak another inch, little GoCars are eco-friendly alternatives, as they go 60 mpg. The first-ever GPS-guided "storytelling" cars, speaking five languages, open-air, bright yellow GoCars are seen zipping around the city to such "green" places as Golden Gate Park, the Presidio and Baker Beach, often ending with a thrilling descent of one of the crookest streets on the planet, Lombard Street.

IF YOU GO

California Nature Tours: 415-971-5201; www.californianaturetours.com.

Urban Trek USA: 415-265-8229; www.urbantrekusa.com.

San Francisco Bike Coalition: 415-431-2453; www.sfbike.org.

Bay City Bike: 415-346-2453; www.baycitybike.com.

City Kayak: 415-357-1010; www.citykayak.com.

Segway/Electric Tour Co.: 415-474-3130; www.electrictourcompany.com.

San Francisco City Guides: 415-557-4266; www.sfcityguides.org.

San Francisco Museum and Historical Society: 415-346-2000; www.sfhistory.org.

GoCar: 800-914-6227; www.gocartours.com.

Karen Misuraca is a freelance travel writer. To read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.