A huge tsunami was spotted in the South China Sea barreling toward Hong Kong in 2003.

The vast wave was 10 times the size of the Boxing Day Indian Ocean Tsunami the following year that killed at least 230,000 people – and there were four of them.

It had the potential to decimate the city of 7 million people and cause devastation the likes of which had never been seen.

But it then it vanished.

Scientists were baffled when the tsunami suddenly disappeared of the radar and there now dozens of conspiracy theories flitting around the internet.

The waves were described as “gargantuan” and “spanning an entire ocean” by journalist Andrew Gough.

When experts measured the waves they calculated that they must be at least 500 feet high.

Normally a tsunami would be considered big if it came to 30 feet or 50 feet, but one expert said they could even rise to as high as 2,000 feet.

Now Science Channel’s “What on Earth?” documentary series is delving into the theories around the incident.

This includes exploring the theory that the waves might have been manmade, possibly a test of a sinister and “exotic” marine weapon.

A preview of the documentary shows interviews with experts, some of whom put forward their evidence for the secret super-weapon theory.

Some of the scientists and journalists interviewed said that studies into tsunami causing weapons have been conducted since the 1940s.

Others even said there are people who suspect that tsunami that hit the Fukushima plant in Japan was caused by a weapon

However several other of the scientists interviewed said it was a computer glitch in the satellite imagery.