Tour Maryland’s only show cave in this delightful throwback to America’s roadside attractions.

This small demonstration cave is Maryland’s largest cavern open to the public. It contains more formations per square foot than any other explored cave, and it’s among the most naturally preserved caverns in the world, with a constant temperature of 54 degrees.

Crystal Grottoes formed in Tomstown Dolomite over millions of years. The cellar is mostly horizontal and the corridors are generally high and narrow. Its floors are brown and red clay; sediment covers several passages within one to two feet of the ceiling. 

The 30-35 minute tour covers 900 feet of its passages, or about one-third of the total cave space. There are no streams, although steadily dripping water collects into a small “lake” or tub.

In 1920, a road-building team attempted to collect gravel in the hillside over Crystal Grottoes. A box bit (for bringing explosives) went to the pit, and the crew realized they found a cave. They blasted into the cave, creating the entrance still used to this day. The cave opened to the public in 1922. In 1968, a mapping operation discovered nearly half a mile of tunnels.

A collection of fissure-like passages of unmatched beauty are located inside. The corridors between “Fairyland” and the “Blanket Room” have lovely formations that stand out owing to their pure white surfaces.

The tour begins in a stone structure built against the cliff side. The first room is eight feet underneath the entrance building, 30 feet long, ten feet wide, and 15 feet high. This space once had several formations, but quarrying operations and cleaning of the tunnels eliminated them from all but the west side, where there are plenty of fluids and stalactites. A narrow tunnel six feet high connects the entrance room with the rest of the cave.

A collection of fissure-like passages of unmatched beauty are located inside. The corridors between “Fairyland” and the “Blanket Room” have lovely formations that stand out owing to their pure white surfaces. The ceiling and walls are coated with green-grey residual clay in this area, their contours rivaling its other formations in beauty.

The “Blanket Room”, at 30×20 feet, is the biggest room in the caverns. Wide sheets of stalactites over 20 feet tall resembling a rind of bacon hang from the ceiling.

In 2007, a fire in the entrance building severely damaged the cave. The fire destroyed the energy grid along with the sprinkler system. Its small generator cannot illuminate all the space, making a dark, somewhat spooky underground atmosphere in its caverns.

Crystal Grottoes Caverns is located at 19821 Shepherdstown Pike in Boonsboro, Washington County, Maryland. It takes about 30 minutes to visit the cellars and costs $20 per adult. Some passages are very short, about four meters long, and a few narrow and winding passages, so larger individuals have to take note and travel slowly and carefully. There are plenty of parking spaces and the double bathrooms are well maintained.