Star Realm

The Star Realm is the secret world. It was rumored that the realm is the residence of a certain deity.

Background
Thousands of years ago, the Star Realm was a place that brings happiness to lots of people, just until the day the Star Realm was corrupted by dark demons. It became a world of darkness, and the darkness began to overshadow the whole outside world. Then, a hero came and brought back light to the outside world, and sealed the door to the corrupted Star Realm. Unfortunatly, the Star Realm was remained as the Realm of Darkness just until the era of Mario.

Sea Side Adventure
After defeating Bowser, it was confirmed that Mario and his friends must collect all of the Power Stars scattered all over Sea Side to open the Star Gate. Once Mario find all the Power Star, the gate will open, leading him to the Star Realm.