Free

It's easy to get charged up on vacation -- $10 here, $5 there, and pretty soon your credit card balance looks like the national debt. To keep that from happening, here's a summary of free San Diego activities.

Downtown & Beyond

It doesn't cost a penny to stroll around the Gaslamp Quarter, which brims with restaurants, shops, and historic buildings, or along the Embarcadero (waterfront), and around the shops at Seaport Village or Horton Plaza. And don't forget: Walkabout International offers free guided walking tours, and Centre City Redevelopment Corporation's Downtown Information Center gives bus tours two Saturdays a month.

If you'd rather drive around, ask for the map of the 52-mile San Diego Scenic Drive when you're at the International Visitor Information Center.

The murals in Chicano Park (tel. 619/563-4661; www.chicano-park.org), painted on the support system of the San Diego-Coronado Bay Bridge, are a colorful road map through Mexican and Chicano history. South of downtown (exit Cesar Chavez Pkwy. from I-5), the 70-plus murals represent some of San Diego's most important pieces of public art. The Museum of Contemporary Art San Diego's two downtown spaces are free to everyone 25 and under; for those who have to pay, your ticket will get you into MCA's La Jolla museum for free, if visited within 7 days. Both the La Jolla and downtown museums are also free the third Tuesday of the month.

And you can fish free of charge from any municipal pier (that is, if you bring your own pole). Fishing license is not required.

Balboa Park

All the museums in Balboa Park are open to the public without charge one Tuesday a month. Here's a list of the free days:

First Tuesday of each month: Natural History Museum, Reuben H. Fleet Science Center, Model Railroad Museum, Centro Cultural de la Raza

Second Tuesday: Museum of Photographic Arts, Museum of San Diego History, Veterans Museum & Memorial Center

Third Tuesday: Museum of Art, Museum of Man, Mingei International Museum, Japanese Friendship Garden, Museum of the Living Artist

Fourth Tuesday: Air & Space Museum, Automotive Museum, Hall of Champions Sports Museum

These Balboa Park attractions are always free: The Botanical Building and Lily Pond, House of Pacific Relations International Cottages, and Timken Museum of Art. Free 1-hour Sunday afternoon organ concerts year-round, and free concerts Monday through Thursday evenings in summer are given at the Spreckels Organ Pavilion. There are four free tours of the park available, leaving from in front of the visitor center. Although it's a local best-kept secret, the San Diego Zoo is free to all on the first Monday of October (Founders Day), and children under 12 enter free every day during October.

Old Town & Mission Valley

Explore Heritage Park, Presidio Park, or Old Town State Historic Park. A 1-hour walking tour of Old Town is conducted twice daily. There's free entertainment (mariachis and folk dancers) at the Plaza del Pasado on Saturdays and Sundays, and the Old Town Market (San Diego Ave. and Twiggs St.), has costumed storytellers. Mission Trails Regional Park, which offers hiking trails and an interpretive center, is reached by following Highway 8 east to Mission Gorge Road.

Mission Bay, Pacific Beach & Beyond

Walk along the beach or around the bay -- it's free, fun, and holding hands at sunset is a proven aphrodisiac. Bring a picnic lunch to enjoy on the Ocean Beach Pier or the Crystal Pier in Pacific Beach.

La Jolla

The half-mile Coast Walk between the La Jolla Cove and Children's Pool is San Diego at its most beautiful -- dabble in the tide pools along the way and enjoy the harbor seal colony at Seal Rock and the Children's Pool.

It's also fun to meander around the campus of the University of California, San Diego, and view the Stuart Collection (bring a pocketful of quarters for the hungry parking meters). The main branch of the Museum of Contemporary Art San Diego is always free to those 25 and under; a paid ticket will get you into the downtown spaces for free (within 7 days). MCASD's museums are all free on the third Tuesday of the month.

Watching the hang gliders and paragliders launching from the Gliderport near Torrey Pines is a blast. For a great vista, follow the SCENIC DRIVE signs to Mount Soledad in La Jolla and a 360-degree view of the area.

Coronado

Drive across the toll-free San Diego-Coronado Bay Bridge and take a self-guided tour of the Hotel del Coronado's grounds and photo gallery. A walk on beautiful Coronado beach costs nothing -- nor does a lookie-loo tour of the neighborhood's restored Victorian and Craftsman homes.

Farther Afield

You can self-tour the U.S. Olympic Training Center in Chula Vista year-round (open daily, except Mon), or take a guided tour during the warmer months. This is the country's first warm-weather, year-round, multisport Olympic training complex. It's on the western shore of Lower Otay Reservoir in Chula Vista, and is one of four United States Olympic training centers. Visitors can see a 10-minute film about the Olympic movement, shop in the gift store, and then check out the highlights of the 150-acre center. Guided tours take place Tuesday through Saturday at 1:30pm. Call tel. 619/656-1500 or go to www.usolympicteam.com for more information. To get there, take I-805 south to the Olympic Parkway exit, and then go east 7 miles until you reach a sign directing you to the Copley Visitor Center; turn right.