The rocky coast around St Julian's has several good dive and snorkel sites accessible directly from shore. The water clarity is excellent by Mediterranean standards, and the rocky reefs at depths of 5–25 metres hold octopus, moray eels, bream, and the occasional seahorse. Several dive centres operate out of St Julian's and Paceville, offering PADI courses and guided dives for beginners as well as experienced divers.
Merkanti Reef, just offshore, is one of the more accessible sites — reachable by boat from the Portomaso area. St Julian's is also convenient for boat dives to the deeper sites around Malta's north-east coast, including the Blue Lagoon area at Comino and several deliberate wrecks. Dive centres include Maltaqua and Aquatica Dive Centre, both with good reputations and multilingual instructors.