Christian,
How was your dive? We just got back from Gran Canaria and our scuba adventures were pretty underwhelmed. As seasoned divers, we are accustomed to diving around a LOT of fish, something we refer to as a 'fish soup.' While we see a couple of brief videos for Gran Canaria's "fish soup," we were disappointed by their absence. I could the varieties of fish (one of each species) on one hand. We saw a small school (less than 20 fish) of white seabream, but that was as soup-y as it got. Ok, sure - in El Cabron, we saw a LOT of sea cucumbers....but, well...it seems like that 'fish soup' in Gran Canaria is a rare occasion. You will need a 5mm or 7mm wet suit as the water is pretty cold. If you chill easily, I recommend a 7mm.
We dove with a couple of dive schools - Extra Divers has excellent guides, but the woman in the shop helping with their sub-par equipment took the shine off. Extra Divers do have access to boat dive spots, although parking by the hotel is a long walk. Lunch can be had at the hotel bar.
My favorite, Davy Jones Diving, had excellent equipment and had a robust dive base that was the most relaxed I've ever gone with. The dives are all shore dives, which can be a bit obnoxious to get in and out, but totally do-able. Parking is easy in the industrial area and they drive you to the shore dive. Lunch (a sandwich) can be purchased about 500m away and drinks are free at the base (soft drinks, juices, coffee, tea, water, you name it!).
We were going to go with Puerto Rico diving, but it turns out they go to the same spots as Davy Jones and the Davy Jones base was too good to leave. Besides, Puerto Rico diving had a lot of divers. The staff was VERY friendly when I contacted them before I got to the island.
Overall, Gran Canaria was over-inflated. I'm happy to hear of other experiences.
Best,
Anna