- Learning to dive in the Quad Cities has never been easier. Sentry Scuba has been serving the Quad Cities and surrounding areas since 1982. With our experienced staff, we pride ourselves in taking the time to teach you right the first time. Here at Sentry you receive plenty of practice in the pool to ensure you master every diving skill 100%. We offer flexible and convenient classroom times to fit into almost any schedule. Whether you want to get started for the first time, or are looking to continue your education, you can trust Sentry Scuba for all of your diving needs in the Iowa and Illinois Quad Cities and surrounding areas.