The Grotto is the world's second cave diving site, located in the northeast corner of Saipan Island, is Saipan's most famous but difficult diving site, it can be said that "without the Blue Hole, Saipan will not be counted. It is said that diving at 5 a.m. is bound to encounter all kinds of turtles, sharks and tuna. After wearing all the equipment, we took frog shoes and walked down the cliff with ducks down more than a hundred slippery steps. It's not fun to fall steeply and slippery. It's really heartbreaking. Travel Strategy - "Accommodation - "Star Sha Hotel is very good, the price is very good, and the environment is also good to eat - "Ni@Seafood@Dining Room, English name - "Tony Seafood restaurant environment is very good, seafood taste is very good, all kinds of seafood transportation - "I recommend QQ car rental, is a very good local car rental company three places are together, more convenient to recommend.