Mark Zuckerberg may be building a 'doomsday bunker' in Hawaii: Here's all you need to know

In addition to two mansions, Zuckerberg's project is one of the most expensive private construction projects in North American history, involving the construction of an entire village of outhouses, the report said.

Dubbed the ‘Garden Isle' due to its tropical rainforest cover, Kauai's most notable feature is the Na Pali Coast in the north, where towering cliffs plunge into an azure sea. The coast has been featured in numerous films, including South Pacific, Jurassic Park, and Pirates of the Caribbean.

The sprawling compound is already under construction the Zuckerbergs reportedly call it 'Koolau Ranch'.

The compounds have two mansions at the center, with a total floor area of 55,000 sq ft, which is similar to that of an American football pitch. These houses offer lifts, offices, conference rooms, and 'industrial-sized' kitchens, Daily Mail reported.

Besides this, there will be another building that will feature a full-size gym, pools, a sauna, a hot tub, and a tennis court.

As per the plans filed with the Hawaiian planning authorities, there will be an underground tunnel that will run between the two mansions and branch off into a 5,000 sq ft underground bunker, the report said.

Earlier, Wired reported that the property will be entirely self-sufficient, having 18 feet-high and 55 feet-wide water tank and a powerful 'pump system'.

As per the report, the subterranean bunker will have a living space and mechanical room and will feature a blast-resistant concrete and steel door.

The exits and entrances throughout the property will have doors with keypad locks and soundproofing, while a library will feature a secret or ‘blind’ door, the report stated.

According to a worker, cameras are installed “everywhere” around the compound.