The Safe Hour was a period of time during which Matoran of Mahri Nui felt they could wander beyond their borders without risk of harm. Careful observation had revealed that there was one hour of the day during which no predators were active in the waters. The primary activity during this time was the harvesting of airweed by Matoran with the aid of Hydruka.1
Notes
The Safe Hour was the one hour when no sea predators were active, so prey fish could swim in safety.2