Most diving sites and facilities can be found in the Algave, the Azores and Madeira. All Portuguese dive sites are situated in the Atlantic Ocean which means that visibility is ranging from fairly good along the Portuguese coast (5 – 8m on average, such as in the Algarve), to clear waters with great visibility at the islands (15-20m+).
In the seas around Madeira, there are various (large) fish species that are not found in many other European waters. Tuna, albacore and marlin are all to be found in these waters. For diving, the Garajau Nature Reserve is well known, while the seabed around Porto Santo provides some good underwater scenery.
Diving in the Azores is a spectacular and the best location for diving in Portugal: the seas around the islands of São Miguel, Santa Maria, Pico/Faial and Flores have much of interest to offer divers. The southern part of the islands are a great base to banks, Islets (Formigas) and underwater mountaints/volcanos that attract large marine life, including sharks, whalesharks and Mobulas (Devil Rays).