Malta is a great place to dive, with it being possible to dive all year around. The water temperature varies from a cool 14°C in February/March to warm 26°C in August. The visibility of water is generally high, making it a good place to learn diving as well.

The dive sites are located close to shore. Consequently, most dives start there, making everything easier and cheaper. The dive sites include rocky reefs, some wrecks and cave diving (especially interesting is the dive in the Inland Sea in Gozo). There will tend to be more marine life during the warmer months, when you can hope to see tuna, octopus, moray eels, seahorses, fire worms, soft coral along with the usual sea grass and underwater ridges.

source: http://wikitravel.org/en/Malta