This huge unguarded dam has become the go-to hidden waterpark for locals to enjoy - tucked away in a forest in the Philippines.

Footage shows youngsters plunging down the 250 metre-long concrete bank of the National Irrigation Administration (NIA) dam in the remote town of Bansalan in Davao del Sur province.

The structure was built in 1978 on the Talomo River to provide irrigation water to surrounding farmlands and potable water to homes.

But it is now doubling up as an adrenaline-busting waterpark slide. Locals and even tourists visit the area to ride the flume and splash in the cool fresh water pool at the bottom and have picnics.

The dam has remained open to the public without guards or entrance fees, mainly due to a lack of manpower to assign to the far-flung area and other budget constraints in the southern part of the archipelago.