I have thought long and hard about this review - because overall my personal experience with Aquamarine and Rehan has been very positive, and I hesitate to give a poor impression. He was very helpful, friendly and accommodating. We had a mixture of experienced wreck divers and one novice in our group and Rehan made sure that we all got to do the dives we wanted. His dive guides are among the best on Santo (Dave Tony has been with Aquamarine since the early days with Kevin & Mayumi Green) and know all the best dives and hidey-holes on the wreck, but - see my proviso later in this review. We were offered Nitrox, twins, etc (but we all dived on air with singles and did the Galley/Stern no probs - just ensure you have plenty of sling tanks and spares at the deco stops!) As other reviewers have noted, the bus was on time every morning and afternoon and the staff are friendly and good fun. Though I'm not sure how long the bus will hold together!
HOWEVER - Rehan had quite a bit of equipment stolen, including wetsuits, BCs, regs, masks/fins, etc. This was a while ago, and doesn't really excuse the current condition of the gear. He also operates from his house now, rather than a dive shop and I don't know what facilities he has there, but the odd bit of equipment he provided was in very poor condition. The regs on the drop tanks breathed wet and the couple of times I needed to use one, the mouthpieces were very univiting, having obviously not been thoroughly washed inside. I'm sceptical about how often the equipment is serviced professionally. Make sure you take a spare torch, because their torches are prone to failure and you may have to lend one to your dive guide! ( We did a deep penetration dive from Galley to Anchor Locker with me and my buddy providing all the light and computer info, due to our guide's equipment failure!) Our one novice diver had her own dive guide, which was great - but these very experienced guys tend to get a bit blase and "do their own thing", expecting their tourists to keep up with them. Our girl chewed through her air and, when she was needing a sling tank, her guide was too far ahead to reach and wasn't checking on her - she ended up having to buddy breathe with her husband back to the deco stop, which was stressful for both of them. On another occasion, an experienced diver returning from a deep dive against strong current had the same thing happen, she was struggling and I had to race to catch up with our guide to point this out.
Bottom line is: if you're an experienced diver with all your own gear, I would recommend Aquamarine without hesitation, for a relaxed and enjoyable dive trip, with knowledgable guides and friendly, helpful service. If you're a novice, or need to hire gear, go with Allan Power (grumpy as he is, he still runs a professional operation!)
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.