Restrictions: The channel crossing is usually tough; no Expecting lady, no one with neck or back injuries, and no children underneath 5 are permitted. Full deal with snorkels are usually not permitted. The beaches are tough and rocky, but included in pure white sand coveted by builders on Waikiki Seashore, https://snorkelingniihauisland66555.ssnblog.com/33894624/the-ultimate-guide-to-niihau-boat-tour