I visited Koh Tao in February and dived on five days with Big Blue. Unfortunately, during the trip the visibility under water was atrocious, almost every day. Not the fault of the dive shop. The scale of the dive shop seems almost on an industrial scale, and yet they get most things correct. On some days on the boat there were more than 50 + people - divers, guides, students etc, and yet, I had a great time. They seemed to be able to divide divers appropriately into small groups and I almost received one on one attention. I cannot say enough nice things about all the dive masters that I dived with, the space is just too less. I thoroughly loved the trip. I would love to go back and dive with them again.