Abstract
This paper reports on a study of AREEF, a multi-player Underwater Augmented Reality (UWAR) experience for swimming pools. Using off-the-shelf components combined with a custom made waterproof case and an innovative game concept, AREEF puts computer game technology to use for recreational and educational purposes in and under water. After an experience overview, we present evidence gained from a user-centred design-process including a pilot study with 3 kids and a final evaluation with 36 kids. Our discussion covers technical findings regarding marker placement, tracking, and device handling, as well as design related issues like virtual object placement and the need for extremely obvious user interaction and feedback when staging a mobile underwater experience.