Like its cousin, the better known fallout shelter, the Tsunami Survival Pod is something you hope you never have to use.

As its creator, the Australian houseboat builder Matthew Duncan, told Wired, “Obviously, yes the safer option is to get to higher ground. Sadly, thousands of people in Japan had no other choice.” Struck by the images of devastation of the 2011 tsunami there, Duncan sprang into action to design his pod, which built upon his extensive experiment making steel-hulled houseboats.

The pod’s cylindrical shape helps it resist the force of waves. “The formulas used to design a boat hull were used when designing the TSP,” Duncan said. “[A]s when building a boat all the displacement, crush forces and center of gravity are all calculated before you start.” Outside the pod, circular impact bumpers protect the pod from smashing devastatingly into other large objects, while internal ring frames and vertical impact bumpers will help secure passengers against various forces. A beacon blinks to help alert rescue workers. Inside the pod, which seats four people and has air capacity to last 2.5 hours, racing harnesses and helmets are worn to help secure and protect the passengers.

Other features, per GovTech, include a secondary hatch (in case the pod is pinned upside-down), inch-thick viewing windows for the claustrophobic, and helicopter lifting hooks. Duncan reportedly studied hours of tsunami footage to get a sense of just how the debris swirled and tumbled in the waves.

The design that Duncan made would run about $8,500; manufacturers are interested despite the hefty price tag, and Duncan is working on a one-person version that he says could even fit under a bed. “I would be happy if I just sold one and it saved four people,” he told the Australian publication Gold Coast. More specs and images of Duncans invention can be found at HavanaHouseboats.com.

Duncan isn’t the only person out there who has contemplated a tsunami pod, as this (extremely unfortunately scored) video shows. Shots of the prototype begin around the 2:50 mark.