In a single dive on the Colombara Reef, it is possible to see an impressive number of groupers, some large enough to weigh in at around 40 kg (88 lb), amberjacks, Mediterranean barracuda, dentex and huge seabream. The reef extends out to sea for half mile from the north coast of the island and reaches up to little more than 3 m (less than 10 ft) beneath the surface of the water.

Dives are almost entirely along the walls, the western side being the most fascinating and considered by many as the most beautiful in the Mediterranean. There is a drop of 14 m (45 ft) to the first plateaux then another that reaches a depth of 42 m (almost 140 ft), which is literally covered with asteroids, parazoanthus and sponges of different species and colours creating a natural habitat for a good variety of sea slugs.

A black cone-shaped sponge at the base of the wall is of particular interest as it recalls a typically tropical setting. Moray eels, rocklings and dark groupers may also be admired in the many crevices to be found all along the wall.

A 74 m mercantile ship, loaded with low-grade marble, ran aground on the reef in and broke-up into two parts in February 2005. The wreck, now resting on a plateau 20 m (65 ft) beneath the surface, can now be visited and is becoming a suggestive habitat for a good number of marine species.