The CAT25 is a totally self-contained 40-150 psi structural fiberglass multiple elliptical torrid underground disaster shelter designed to protect 25 adults for long periods or 50 people for short durations such as during tornadoes. This product was specifically designed and developed to protect people during and after disasters such as tornadoes, hurricanes, earthquakes, storms, forest fires, power failures, nuclear power plant accidents, nuclear/chemical terrorism, and full-scale protracted nuclear, chemical and biological war. A tremendous effort has been made to think of every conceivable incident that shelterists could face in the CAT25 shelter. Many geometrical shapes were experimented with before finalizing the CAT25. The CAT25 includes the fiberglass toroidal structure, fiberglass entranceway, fiberglass/composite hatch, MCAS air filtration system for nuclear-biological-chemical environments, septic system, fiberglass water tank, fiberglass flooring, fiberglass counter, fiberglass shower walls, fiberglass battery housings, two toilets, Forty 12- volt deep cycle batteries, air blower, gray water tanks, all wiring, and all plumbing, etc.