DENNING, N.Y. (AP) — A highly popular Catskills swimming spot called the Peekamoose Blue Hole now requires a permit.

New York environmental officials say a free permitting system will limit use of the Blue Hole to 240 people per day. The Department of Environmental Conservation will provide up to 40 permits a day, for up to six people each.

Officials say they want to ensure access to the spot in the Ulster County town of Denning while reducing environmental damage and keeping people safe.

Crowds swelled in 2015 after national magazines touted it as a top swimming hole in the nation.

Permits are available on . They must be obtained between 24 hours and a week in advance and list the name of every person in the group.