Hanauma Bay, on Oʻahu’s southeast coast, is a volcanic marine embayment formed about 32,000 years ago when underwater eruptions shattered reef and basalt and built a tuff ring later opened by wave erosion. Though it lacked fresh water for permanent settlement, Native Hawaiians long used the area for fishing, recreation, and travel, and aliʻi including Kamehameha and Queen Kaʻahumanu spent time there. In the modern era it became a heavily visited beach, but popularity damaged its reef and wildlife habitat. Now protected as a Nature Preserve and Marine Life Conservation District, the bay is managed through education and strict limits intended to reduce human pressure.