Too bad you can't get to Noronha, but I've heard that Recife and Natal in the northeast have great diving. The following I pasted from a SB thread from a few months back (sorry, could not figure out how to link to it). It impressed me as the most comprehensive post on Brazil diving that I have seen.
Personally, I would recommend Atlantis Divers (see link below), who I dived with on Noronha last year. I believe they have an operation in Natal also. I found them to be very professional and very well organized. There website is available in English and they had English speaking crew in Noronha and probably do in Natal. Enjoy your trip to Brazil.
Quote-
"I’ve listed below (from North to South) the best places where you could dive in Brazil with links to local dive shops. Dive sites have been (subjectively) rated from 1 (best) to 6 (see the number before the city name):
1- National Marine Park of Fernando de Noronha, also known as “Noronha” (pelagics, reef fish, some coral, world class technical dives, from June to November visibility reaches 50 meters; 340 km off the Northeastern tip of South America; 70-minute flight from Natal daily at 8 a.m. and 11 a.m. R$383 one way, or 90-minute flight from Recife daily at 12:00 and 14:30 R$441 one way, it can be included in Varig’s Brazil Airpass; only about 15% of the visitors to Noronha are foreigners);
http://www.atlantisnoronha.com.br/english/default.asp, which is perhaps the best dive outfit in Brazil and the most expensive one,
http://www.aguasclaras-fn.com.br/en_index_corpo.htm and
http://www.noronhadivers.com.br
5- Recife (many old wrecks);
http://www.projetomar.com.br/operacao.html,
http://www.aquaticos.com.br and
http://www.seagaterecife.com.br/novosite/index.php
6 - Maragogi (the town is a good base to dive one of the biggest coral reefs in Brazil, which goes from Maceió up to the town of Rio Formoso; Maragogi is located 130 km north of Maceió);
http://www.maragogionline.com.br/cactusdiving
4- Salvador (many old wrecks, coral reef, visibility = 3-15 meters inside the bay, 6-30 meters outside the bay, where lies the 170-meter-long Cavo Artemidi, which is the biggest ship wreck in Brazil);
http://www.divebahia.com.br,
http://www.bahiascuba.com.br and
http://www.uwbahia.com.br
3- Morro de São Paulo (coral reef; 2 hours by boat south of Salvador, visibility = 5-20 meters);
http://www.ciadomergulho.com.br Gustavo and Sandra are both instructors who have been diving for almost two decades and speak several languages; they always made our dives a very enjoyable experience
2- National Marine Park of Abrolhos, also known as “Abrolhos” (coral reef, humpback whales from late July to early November, wrecks, also very good for snorkeling, visibility = 10-40 meters; it was the first Marine Park created in Brazil in 1983 and is 1.5 to 3 hours away by boat from the town of Caravelas, which is half way between Rio and Salvador. There is a direct bus from Salvador to Caravelas on Fridays at 7 p.m. and back on Sundays at 4:50 p.m., also several daily buses from Salvador to Teixeira de Freitas, where you change to another bus to Caravelas. Leaving from Porto Seguro, there is a daily bus to Caravelas at 2 p.m. and several daily buses to Teixeira de Freitas). Daytrips and liveaboards:
http://www.abrolhosembarcacoes.com.br/ingles/index.htm and
http://www.paradiseabrolhos.com.br. Liveaboards only:
http://www.horizonteaberto.com.br,
http://www.titanliveaboard.com.br,
http://geocities.yahoo.com.br/catama...k/catamara.htm and http://www.abrolhosdive.com.br/maritimo.htm"
