Nitrox 32% is fairly readily available, even though now only one shop (Amigos) produces it. The shops which sell it - most of them - don't generally have oxygen analysers, so if you have your own bring it. This is actually good terrain for recreational nitrox, as most diving is in the 60ft-100ft region. Much deeper than that you can't use it, shallower you don't need it. I don't know where you get the idea that you might not need it if the diving isn't "deep". I recommend you use air for the first dive of the day and consider nitrox for subsequent dives. As yakivet says above, hitting decompression limits is your main problem here, and whilst that won't often happen if you're using nitrox it still can.
Good to see Carlos back in here. I knew he had steel tanks up there but I couldn't remember if there were 100's. Clearly there are. They have an air compressor but AFAIK don't yet have the facility to produce nitrox. For anyone wanting to come here but undecided where to stay & dive, I can strongly recommend TBR. Accommodation, food, ambience and diving (both what you actually see down there and the flexibility to organise it to your own requirements) are all first rate. Staying next door at Sueno del Mar and diving with TBR is the next best.
