Best For
Snorkeling, diving, and witnessing dramatic natural cave formations.
The Grotto is Saipan's most iconic natural attraction, a collapsed limestone cavern that connects to the open ocean through underwater tunnels. Located in I Maddok, this site is famous for its ethereal blue light and crystal-clear visibility, making it a bucket-list destination for divers and snorkelers alike. Visitors descend a steep staircase of over 100 steps to reach the water's edge, where the sheer scale of the cave—often compared to a massive cathedral—becomes apparent. While the trek back up can be strenuous, the opportunity to swim in such a dramatic, light-filled cavern is widely considered a highlight of any trip to the Northern Mariana Islands.
The Grotto is Saipan's most iconic natural attraction, a collapsed limestone cavern that connects to the open ocean through underwater tunnels. Located in I Maddok, this site is famous for its ethereal blue light and crystal-clear visibility, making it a bucket-list destination for divers and snorkelers alike. Visitors descend a steep staircase of over 100 steps to reach the water's edge, where the sheer scale of the cave—often compared to a massive cathedral—becomes apparent. While the trek back up can be strenuous, the opportunity to swim in such a dramatic, light-filled cavern is widely considered a highlight of any trip to the Northern Mariana Islands.
Crystal-clear deep blue water inside a massive limestone cavern.
Unique underwater karst cave reaching depths of 70 feet.
Dramatic cliffside scenery and a cathedral-like atmosphere.
Popular spot for both guided snorkeling and professional diving.
Snorkeling, diving, and witnessing dramatic natural cave formations.
Tourists, Groups
The Grotto is widely celebrated as a breathtaking natural wonder and a must-visit destination in Saipan. Reviewers are consistently mesmerized by the crystal-clear, deep blue water and the dramatic scale of the limestone cave, which some compare to a massive cathedral. While the scenery is stunning, many visitors highlight the physical challenge of the 117 steep, narrow stairs required to access the water. Most recommend visiting as part of a guided tour, especially for snorkeling, as guides provide essential assistance with water entry and exit. The site is noted for being well-maintained, though it can get crowded with tour groups. Overall, it is described as an awe-inspiring experience for both divers and casual swimmers, provided they are prepared for the hike back up.