Saturday

3. ­Juice and Shine, 10 a.m.

Morning is a great time to visit San Sebastià beach, which due to its proximity to the port and city center gets very crowded as the day wears on. Breakfast at La Guingueta de la Barceloneta by Carles Abellan – the Michellin-starred chef of Commerç 24, Tapas 24, and Bravo – includes “super juices” that promise to boost your tanning ability with a blend of carrot, orange, melon and spinach juice or help you recover from a hangover (orange, tomato, red pepper, and sage juice).There’s also artisanal yogurt with berries and muesli, thick wedges of Spanish omelet, and pan con tomate – toasted bread rubbed with garlic and fresh tomato and then drizzled with olive oil that can be topped with succulent slices of ham or just devoured on its own.

4. ­Stay Dry Underwater, 11 a.m.

For history buffs, those traveling with children, or anyone hoping to get out of the sun for a spell, there are worthwhile city attractions clustered around the old port. Start with the city aquarium (20 euros for adults, 18 if purchased online), which takes only 30 to 45 minutes to visit and requires little effort as you stand on a conveyor belt that winds through glass tunnels beneath stingrays and sharks swirling in the waters above. Across the Passeig de Colom is the Museu Maritim (7 euros), situated in the old royal shipyards. Parts of the building date from the 15th century, with stunning stone and wood vaulted architecture that is almost as engaging as the ships and seafaring paraphernalia sheltered within it. As you make your way back toward the beach, step aboard the Santa Eulalia, a 154-foot, three-masted schooner built in 1918, moored in the harbor; a self-guided visit is included in the price of the museum (or 3 euros on its own).

5. ­Merchant Marine, 1 p.m.

Over the centuries Catalans have developed a penchant for the decorative arts with items like sweet-faced ceramic dogs, jewel-tone glass and little silver platters with kooky enamel ornaments appearing in quantity at flea markets like the one called Fira Brocanters, which takes place Saturdays and Sundays in the port. As thoughts turn to lunch, stop for a beer or glass of rosado and a plate of pescaito frito — fried sardines so tiny they are eaten whole and by the handful — at Jai-Ca, one of the few places in La Barceloneta where it almost feels as though locals outnumber tourists.

6. ­Global Beach Food, 3 p.m.

Xiringuito Escribà on Bogatell Beach north of the Olympic Port always ranks among the city’s top seafront dining establishments for simple grilled summer fare — a xiringuito (or chiringuito) is a restaurant on the beach. In 2013, Escribà opened a second, smaller beach shack, La Guingueta, right down on the sand, which was an immediate hit with locals. Mix-and-match a tapas lunch of grilled razor clams, tangy lime and cilantro ceviche, tender octopus dusted with pimentón, and some of the best guacamole this side of the Atlantic.

7. ­ Beach by Any Other Name, 6 p.m.

Hotel concierges and the city’s tourism board describe the neighboring beach known as La Mar Bella as the perfect spot for a young “cosmopolitan crowd from all walks of life,” including “naturists,” tourism code for a gay beach. When you tire of staring at the sea or the buffed and polished crowd, there are two outdoor gyms and a small skate park nearby. As day turns to evening, cocktails and sangria replace the protein shakes turning up on most tables.

8. ­ Sailfish, 9:30 p.m.

Run by Tragaluz, the Barcelona restaurant group that sets the standard for stylish dining in the city, the beachside restaurant Pez Vela has a groovy vibe and a multilevel dining room that maximizes people-watching. If you’re riced out, try the burger or an unexpectedly delicious salad of artichokes, celery, tomatoes and ribbons of a buttery mahón cheese. Upon arrival, ask the hostess if you can be added to the door list at Eclipse Bar, upstairs at the W Hotel. If she declines, develop a relationship with your waiter and ask again. Otherwise when dinner wraps around midnight, tough out the line to take the elevator to the 26th-floor bar where the city celebrates some of its biggest parties and premieres overlooking the endless Mediterranean horizon.