You probably mean that island, where Lona can end up if washed away into sea?
Find any shore on the map, and go across it, for as much steps as needed.
Big wave would appear, don't resist and let it wash you away into sea... There are random chances to end up on any other shore on the map, including that island which is naturally off limits... That's quite an adventure btw. 😘
Spoiler alert:
There's a previous ship that went off the Noer island with refugees, which crashed on that island leaving everyone stranded...
Same ship carried seeds of parasitic flower 🌺(aphrodesiac drug), and whole island ended up sprawling with this plant... It also being the dominating food source there, except for few fish and bananas.
So you can figure out what the stranded crew ended up doing, and what would happen to Lona. 🙂
Also, better leave your stuff at Tripartite Exchange bank, because each time you're washed away into sea – a lot of your gear is lost.
Also, it's possible to make a good bit of money by collecting as many parasitic flowers 🌺 while at the island , and then selling 100s of them upon return to Noer.
*cha-ching* 👧🏻