Mollys Castle is a remote 5,265-foot (1,605-meter) elevation summit located near Goblin Valley State Park, in Emery County, Utah.

[3] Precipitation runoff from Mollys Castle enters the Colorado River drainage basin.

The thin, light-colored layer on top is Curtis Formation caprock, overlaying darker, reddish Entrada Sandstone, which is also the composition of the hoodoos that give Goblin Valley its name.

According to the Köppen climate classification system, it is located in a Cold semi-arid climate zone, which is defined by the coldest month having an average mean temperature below −0 °C (32 °F) and at least 50% of the total annual precipitation being received during the spring and summer.

[6] This desert climate receives less than 10 inches (250 millimetres) of annual rainfall, and snowfall is generally light during the winter.