I've actually been there a couple of times.. to Cayo Guillermo (beside Cayo Coco), as well as Jibacoa. The dive shops are pretty primitive, but the diving is beautiful. There are many swim throughs, corals, and fish galore. There are even caves, but I doubt you'll find anyone to take you to them. They are way off the beaten path. The dive boats are quite small (my experience at both locations), and the waves can be both non-existant, as well as throwing you all over the ocean.

Here's a pic of the the dive boat at Jibacoa...



At Jibacoa, there is also amazing snorkelling (even though I am not a big snorkelling fan). The reef starts about 20' from shore, and is home to approximately 120 species of fish in that area alone. I saw puffer fish, spotted rays, and many other "neat" things just snorkelling.

Keep in mind that my camera wasn't the greatest...

This was taken while snorkelling in Jibacoa...



While diving in Cayo Guillermo...



The dive crew at Jibacoa were amazing. Although they weren't a "state of the art" dive shop, the people were very accomodating. I would recommend bringing your own regs, BC, wetsuit, fins, mask, and yes... even a snorkel.

Cayo Guillermo was ok, the diving decent, but if I had to choose between the two, I would pick Jibacoa again. The resort had better food, more to see, and a bigger dive team.

Cayo Largo is supposed to have some incredible diving, but it can be a tough spot to get to, as the weather etc. can be very unpredictable. I recommend the end of May/early July for the Northern spots, such as the places I went.

If anyone would like some more info, don't hesitate to ask!