HONOLULU—Paradise has a sewage problem.

Cesspools—holes in the ground where untreated human waste is deposited—have become a crisis in Hawaii, threatening the state’s drinking water, its coral reefs and the famous beaches that are the lifeblood of its tourist economy.

Sewage from cesspools is seeping into some of Hawaii’s ocean waters, where it has been blamed for infections suffered by surfers and snorkelers. It is also entering the drinking water in part of the state, pushing nitrate levels close to the legal limit.

Hawaii has 88,000 cesspools across its eight major islands, more than any other state. Collectively, they deposit 53 million gallons of raw sewage into the ground every day, according to the state health department. More than 90% of the state’s drinking water comes from groundwater wells.

State lawmakers, who outlawed new cesspools in 2016, are scrambling to find a solution to the thousands that exist.