The Grotto area on Saipan centres on a natural limestone cavern that opens to the ocean, and the sites here are suited to intermediate and advanced divers. The namesake cave descends to around thirty metres on average, with visibility regularly reaching the upper end of the fifteen-to-thirty-metre range. Spot Light, a boat-access cave site, is defined by vertical light shafts and an air pocket within the cave structure. Banzai is a wall site dropping to thirty metres, with boat-only access during the higher-wave summer months. Species across the three sites include whitetip reef sharks, green sea turtles, Napoleon wrasse, giant morays, day octopuses, and nudibranchs. Surge and currents near tunnel exits require careful dive planning.
Monthly water temperature across The Grotto's sites, from satellite sea-surface data corrected for depth. The band shows the site-to-site spread.
Water temperature is warm all year, dropping only slightly in the early months. The cave environment means conditions inside can differ markedly from those outside, and surge at the exits is a real consideration. Banzai's access is restricted to boat entry during the summer months due to elevated wave activity.
1 operator
Water temperature around The Grotto ranges from about 28°C in January to 30°C in June, based on satellite sea-temperature data for its dive sites.
With water around 28–30°C, a rash guard or 3mm shorty works in The Grotto year-round.
Fin maps 3 sites in The Grotto (3 scuba diving sites).
