Muscle Bay is an outdoor gym seen in Lilo & Stitch: The Series. It is much like a health spa, where muscular athletes go to work out and where boxers participate in boxing. The beach gym provides barbells, punching bags, and monkey bars for athletes to tone and condition their muscles. The gym also contains a lake for swimming and a boxing ring for boxers to practice on other opponents and take part in boxing matches.
In "Kixx", a group of athletes are seen working out at Muscle Bay when Experiment 601 (Kixx) suddenly attacks the beach gym and defeats all the boxers with ease. Stitch eventually arrives and challenges Kixx to a rematch, since the latter had gotten the best of Stitch once before. At first, during their long-drawn-out-battle, 601 is able to easily overpower Stitch in combat. However, with Lilo's training, which included using a special book titled Fighting Four-Armed Monsters, Stitch is able to block and counter all of Kixx's blows easily. Stitch then uses all the tactics that Lilo had taught him (as well as items around the beach gym) and eventually defeats Kixx by restraining him with the ropes from the boxing posts. After Kixx is rehabilitated, he is found a one true place teaching people kickboxing while hosting his own workout video, as Stitch pointed out to Lilo that teaching is good.
In "Angel", Kixx is seen hanging out at Muscle Bay. Angel then arrives at the gym and reverts Kixx to evil again by singing her siren song. Later, when Stitch arrives at the gym, Kixx is seen beating up some athletes. Confused by this, Stitch is forced to battle Kixx again and defeat him.