The original Fuerte de San Diego, Costera Alemán, east of the zócalo (tel. 744/482-3828), was built in 1616 to protect the town from pirate attacks. At that time, the port reaped considerable income from trade with the Philippine Islands (which, like Mexico, were part of the Spanish Empire). The fort you see today was rebuilt after considerable earthquake damage in 1776, and most recently underwent renovation in 2000. The structure houses the Museo Histórico de Acapulco (Acapulco Historical Museum), with exhibits that tell the story of Acapulco from its role as a port in the conquest of the Americas to a center for local Catholic conversion campaigns and for exotic trade with the Orient. Other exhibits chronicle Acapulco's pre-Hispanic past, the coming of the conquistadors (complete with Spanish armor), and Spanish imperial activity. Temporary exhibits are also on display. Admission to the museum is $3.50. The new Foro Cultural Multimedia, a spectacular light-and-sound show, starts at 8pm in Spanish, with special accommodations and shows available for groups in English afterward. Enter at 7pm to have enough time to tour the museum before the show; the $10 charge includes museum admission. Call in advance to make group reservations for English shows.

To reach the fort, follow Costera Alemán past old Acapulco and the zócalo; the fort is on a hill on the right. The museum is open Tuesday through Sunday from 10am to 5pm, and the best time to go is in the morning, because the air-conditioning is minimal. Admission to the fort is $1.60; free on Sunday.

The Centro Internacional de Convivencia Infantil (CICI), Costera Alemán at Colón (tel. 744/484-8033), is a sea-life and water park east of the convention center. It offers guests swimming pools with waves, water slides, and water toboggans, and has a cafeteria and restrooms. The park, which recently underwent a $3 million renovation, is open daily from 10am to 6pm. General admission is $6 weekdays, $8 weekends, and free for children under 2. There are dolphin shows (in Spanish) weekdays at 2 and 4pm, and weekends at 2pm. There's also a dolphin swim program, which includes 30 minutes of introduction and 30 minutes of swim time. The cost for this option is $95, with shows offered at 10am, 12:30, and 4pm. Reservations are required; there is a 10-person maximum per show for the dolphin swim option. Minimum age is 4 years.