I’m currently unable to find much information on the site, it was a jet mine at some point, later converted for water storage.
Possibly for the nearby Gribdale Terrace when the Ayton Bank and Ayton Monument ironstone mines were operational.
The mine is accessed via a tight tunnel with a water pipe down the center.

Inside the mine has concrete dividers storing deep pools of water, and a ladder leading vertically into the woodlands above.

The ladders look very unsafe so its best to back track through the tunnel and look for them in the woods.

The actual site can be a bit tricky to locate. Either come at it from the lower path where you can just make out a slight clearing heading towards the tunnel entrance, or follow the line of the wall from the top path looking for the hatch.