School of Sargent Major fish fills the water above a shallow pinnacle on a coral reef in the Gulf of Thailand, darting and swimming

approaching swimming shallow pinnacle coral reef sergeant major fish damselfish koh tao thailand ocean gulf tropical blue turquoise clear transparent saltwater open water underwater snorkeling scuba diving freediving sunny sun rays bright reflections island handheld afternoon late school shoal group beautiful pristine conservation ecology diversity biodiversity nature marine wildlife animal colorful aquatic environment