The Grotto
A limestone sea cave on Saipan's northeast coast. A pool inside connects to the open ocean through three underwater passages, making it a world-famous cave dive site.
The Grotto lies in the Marpi area in the northeast of Saipan. It is a huge vertical cave formed when a limestone coast collapsed, and it holds a pool of seawater that connects to the open ocean through three underwater tunnels. When sunlight enters through the opening, the water turns a deep gem blue, which gives the cave its name. Visitors can descend more than 110 steep steps to the viewing platform at the bottom, and there is also an overlook above the opening. For divers, the Grotto is a world-renowned cave dive site. Diving down through the pool and along the tunnels into the open ocean reveals 'blue light' streaming through the opening, coral cliffs and schools of fish. It suits experienced divers led by professional dive guides, and local dive shops offer introductory dives. Note that swells from the open sea often surge into the cave, making the currents and waves dangerous. Do not enter the water when the waves are high, and non-divers should not jump in or swim. The steps are slippery. Viewing is free. Getting there: about 25 minutes' drive from Garapan, on the same northern loop as Bird Island and Banzai Cliff.
Opening hours
All day (daytime recommended)
Nearby sights
- Bird Island
- Suicide Cliff
- Banzai Cliff
- Last Command Post Park
- Kalabera Cave
- Wing Beach
- Pau Pau Beach
- Japanese Lighthouse (Navy Hill)