We were in Chania for vacation, and wanted to snorkel in the beautiful waters there. There were many different companies offering snorkel tours, but ultimately we went with Omega. I think they were a few dollars pricier, but they seemed the most professional and specialized in actual snorkel and scuba tours.
The staff were very friendly, and able to accomodate my wife who is pregnant. We were worried that the waters would be too choppy, but the captain was nice enough to slow down the boat so that she wouldn't get sick. We had a blast in the water, and saw many aquatic animals.
The water was a bit cold, but the tour included full body wetsuits, fins, masks, small lunchbox, and underwater photo/video without any additional costs. Overall, would def recommend again.