The Fitness Center at Park Hyatt Zanzibar
The fitness center at Park Hyatt Zanzibar is endorsed by professional reviewers. Of the 4 reviews that we tracked, 2 acknowledged the fitness center, such as Condé Nast Traveler and Jetsetter.
Park Hyatt Zanzibar 
 Condé Nast Traveler
 Jetsetter
 "There’s an excellent Anantara Spa and a state-of-the-art fitness center onsite, but the highlight of the property is its 60-foot-long oceanfront infinity pool, which overlooks the entire expanse of Stone Town beach" 
 "You're sure to appreciate the recreational amenities, including an outdoor pool and a 24-hour fitness center"