But it takes a boat tour to really get down to sea level, to look up at the steel underpinning of giant bridges.

The handful of passengers on the Lulu Kai peered over the railing as Capt. Mike Young pointed out some sights in Los Angeles Harbor.

“We’re heading south out of the main channel,” Young said, using the boat’s loudspeaker. “On the left is the Southwest Marine dry dock.” Its huge, submersible platforms, he said, can lift a 22,000-ton ship.

And indicating a long warehouse-like building on the right where commercial fishers bring their catches, he said: “There’s a boat now, pulling up to unload.”

Soon, the Lulu Kai rounded the tip of Terminal Island, with its rocky breakwater, well-groomed lawns and neat stucco buildings with white tile roofs. “That’s Reservation Point, where the higher-ups in the Coast Guard live,” Young said.

But as the boat passed by the east end of the point, the architecture became noticeably more plain and the colors a muted gray. “That’s the Terminal Island Federal Prison,” Young pointed out.

You can see the harbor while driving across the Vincent Thomas Bridge, and you can see it strolling through Ports O’ Call Village or from any number of vantage points in San Pedro.

But it takes a boat tour to really get down to sea level, to look up at the steel underpinning of giant bridges, to move among Navy ships, pass by John Wayne’s former yacht and cruise past towering cranes and jagged mountains at the scrap iron terminal.

And it takes a tour boat captain to recount the history of the century-old harbor--Terminal Island was created by harbor dredging--and the lore of some of the ships riding at anchor in San Pedro Bay.

On this particular sunny afternoon, the Lulu Kai came close enough to the forlorn passenger ship Expex to let people see the grime on its windows. It seems there were plans to turn the ship into a floating resort, but the Coast Guard felt it was not seaworthy, Young explained. That was a year ago, and the Expex has been anchored in the bay ever since.

The Lulu Kai is one of three harbor tour ships operated by Los Angeles Harbor Cruise at the Village Boat House in Ports O’ Call. An hourlong cruise shows you such things as the bay, Angels Gate Lighthouse and the cruise ship terminal that is home to the “Love Boat.” A 1 1/2-hour sojourn adds the Long Beach Naval Station.

Nearby, three other cruise concerns also operate harbor tours, some seven days a week, others on weekends only. One of the companies--Buccaneer-Mardi Gras Cruises--offers cocktails or dinner on board a 1920s Mississippi paddle wheeler or a replica of a square-rigged sailing ship.

Gene Meister, who runs Los Angeles Harbor Cruises, says he takes 50,000 people a year around the harbor--most of them on weekends and during the warm spring and summer months. Visitors come from as far away as Europe and Australia, and as close as local schools whose children tour the harbor to learn about maritime jobs.

On board the Lulu Kai, Peter Duffert of West Germany said one of his hobbies is visiting major ports because of their international flavor. But he said what he was really enjoying was the clear, sunny day.

He was on vacation from his job at the West German Embassy in Poland. “When I left there,” he said, “it was snowing.”

Los Angeles Harbor Cruises, Village Boat House, Ports O’ Call. Hourly tours daily, except Thanksgiving and Christmas, from noon to 4 p.m. Adults, $6; children between ages 2 and 12, $2.50; under 2, free. In addition, 1 1/2-hour harbor and Navy base cruises are offered Saturday and Sunday, 12:30, 3 and 3:30 p.m. Adults, $10; children between ages 2 and 12, $4; under 2, free. Information: 831-0996.

Buccaneer-Mardi Gras Cruises, Berth 76, Ports O’ Call. Hourlong cocktail cruise. Adults, $5; children, $3; 1 1/2-hour dinner cruise, $31 per person. Cruises are Fridays, Saturdays and Sundays. Starting times change weekly. Information and reservations: 548-1085 or 547-2833.

L.A. Harbor Sportfishing, near Fisherman’s Village. Hourly tours daily from 11 a.m. to 4 p.m.; until 7 p.m. on Saturdays and Sundays. Adults, $4; children, $2; infants free. Information: 547-9916.

Spirit Adventures, south end of Ports O’ Call. Seventy-minute tours Saturday and Sunday at 12:30 p.m. through mid-June. Daily tours planned for summer. Adults, $5; children 12 and under, $3; infants free. Information: 831-1073.