Sentry Scuba - The Largest, Most Complete Five (5) Star Scuba Diving Center in the Quad City Area. Sentry Scuba has been in business for over 20 years and with seven (7) PADI Instructors we can teach you Scuba Diving from Beginner level all the way through Instructor. We sale a wide range of name brand Scuba Equipment. We also offer In House Service, Scuba Trips and Air Fills. New to our center is our Enriched Air Nitrox Center. Stop by or call us today for more details at (309-797-9721) or toll free 1-800-443-8625.