The Reptile Den allows easy observation of reptiles and amphibians while in their hiding and sleeping spot without opening the terrarium and disturbing the animals. Digging out animals by removing the substrate and terrarium decoration is an underestimated stress factor that now is completely eliminated. The rock-cover can be removed from outside the tank to observe the hiding and sleeping animals and placed back on the glass. The two pieces are kept together through the glass by strong magnets. The rock is insulated to keep the tunnel system cooler than the ambient temperature inside the terrarium. Some moistened moss or substrate can be placed inside the Reptile Den to keep it moist.