The leatherback sea turtle returns to Playa Grande between October and March, digging nests above the high-tide line in sand that holds steady at twenty-eight degrees Celsius. Las Baulas National Marine Park was established in 1991 to protect the last major Pacific nesting colony of Dermochelys coriacea, a species that has survived sixty million years but now numbers fewer than thirty-four thousand adult females worldwide. The park encompasses twelve hundred hectares of mangrove estuary, dry tropical forest, and five kilometres of unlit shoreline where artificial light has been banned since 1995 to prevent hatchling disorientation. Tamarindo Bay forms the park's southern boundary, a crescent of shallow reef and volcanic rock that shelters spotted eagle rays, whitetip reef sharks, and seasonal aggregations of mobula rays. The catamaran fleet operates under permit from the Sistema Nacional de Áreas de Conservación, departing between four-thirty and five in the afternoon to reach open water before the equatorial sunset, which occurs year-round between five-forty and six-twenty. The Gold Coast — a marketing term adopted in the nineteen-eighties — refers to the thirty-kilometre stretch from Tamarindo north to Playa Flamingo, where the continental shelf drops to two hundred metres within three nautical miles of shore, creating upwellings that draw pelagic species close to the surf zone. A Tamarindo sunset cruise typically follows a northwest heading past Playa Langosta and Cabo Velas, anchoring in fifteen to twenty metres over basalt reef colonised by brain coral, sea fans, and cleaning stations frequented by green and hawksbill turtles. Snorkeling occurs before sunset, when light penetration peaks and parrotfish, surgeonfish, and trumpetfish are most active. The return leg coincides with the last half-hour of daylight, when the Nicoya Peninsula silhouette darkens against a sky that shifts from apricot to violet in under twelve minutes. Tour operators provide life vests, snorkel gear, and a bilingual naturalist required by park regulations. The park entrance fee — twelve dollars per person — is collected separately and funds patrol operations along the nesting beach. Most sailings include an open bar and grilled snacks served on deck after the snorkel session. Booking opens six months in advance; peak season tours between December and April fill within seventy-two hours of release.