Even though exertion-based games (or, exergame) are regarded as promising ways to promote physical activities, most of them has considered ground-based physical activities. To design exergames for water-based physical activities, there are many unique challenges, such as (1) underwater network communication, (2) swimming motion recognition, and (3) game mechanic design.
Exertion-based games (or, exergame) has been considered as a promising way to motivate people to adhere to exercise. There has been a massive amount of exergames succeeded in the marget, ranging from Konami's Dance Dance Revolution to (very recently) Nintendo's Ring Fit Adventure. However, almost all exergames focused on gamifying ground-based exercise, and aquatic exercise has been gained a little attention in an exergame world. Actually, an aquatic environment is very challenging to design exergames, mainly because users' sensory capabilities would be limited underwater so that a very special game mechanic should be required.