Diving and snorkelling are the primary activities. Aqaba Marine Park (administered by ASEZA) protects a long stretch of reef along the south coast. The coral is generally intact and the fish life is excellent. Multiple dive centres offer PADI courses, fun dives, and guided snorkelling; shore diving is possible at several points. Glass-bottomed boat trips are an option for non-divers.
Aqaba Castle (Mamluk Fort) in the old town was originally built in the 13th century, damaged by British naval bombardment in 1917 during Lawrence of Arabia's campaign, and subsequently rebuilt. It houses exhibits on the city's history and is a worthwhile short visit. The small Archaeological Museum next to the castle has coins, pottery, and inscriptions from Aqaba's history as a Red Sea trading port.
The waterfront corniche and the market area near the city centre are good for an evening walk — the city is most pleasant after dark when the heat has eased.