An excursion involving underwater exploration of a marine cavern, typically a sinkhole open to the surface. These formations are renowned for their deep blue coloration, caused by the absorption of most visible light except for blue wavelengths. Participants, equipped with a mask, snorkel, and fins, observe the unique geological structures and marine life inhabiting these ecosystems.
The activity allows individuals to experience unique and fragile aquatic environments firsthand. It fosters an understanding of marine geology and biodiversity, and supports local economies through tourism revenue. Historically, such expeditions have contributed to scientific research and conservation efforts by providing data on these relatively unexplored underwater formations.