Complex sentence: Along with the technological advantages that the venue provides the athletes with, it is believed that the indoor advantages of controlling temperature, humidity and lighting, help the swimmers mentally; even the wide decks are said to give the swimmers a sense of space.
Split into simpler sentences: Along with the technological advantages that the venue gives athletes, some believe that the indoor advantages of controlling temperature, humidity and lighting help the swimmers mentally. Even the wide decks are said to give the swimmers a sense of space.