Complex sentence: In recent years, as the waters of Sanya Bay and others below mentioned are becoming clearer and healthier, several species of dolphins including endangered Chinese white dolphins appear along the coasts from time to time, they have not been considered as targeted tourism attractions.
Split into simpler sentences: In recent years, as the waters of Sanya Bay and others below mentioned are becoming clearer and healthier and several species of dolphins, including endangered Chinese white dolphins, appear along the coasts from time to time. However, they have not been considered as targeted tourism attractions.