“Oh my God, this is going to be amazing,” a preadolescent wearing a gray hoodie exclaimed as he dashed in to The Yard, a 50,000-square-foot adventure playground on Governors Island in New York Harbor.

The Yard, for kids 6 through 13, lacks the usual monkey bars, slides and swings. It is, however, well-stocked with dismembered store mannequins, wooden packing crates, tires, mattresses, an old piano and assorted other detritus of the modern world.

There were a few rules: no iPads or electronic devices, no flip flops and no adults. The paint ed wooden gate is low to disco urage adults from inadvertently wandering in.

Despite a steady rain on Saturday, the opening day for the season, The Yard was a hive of activity. Joey Gunderson, 11, and his crew were attempting — not altogether successfully — to nail together wooden boards and plastic sheeting to construct a ramshackle “house.”