Incredible footage shows the impact of nuclear bomb being tested underwater

A horrifying clip shows what it looks like when an atomic warhead is detonated underwater.

This particular explosion was recorded in 1958, and shows a Mark 7 nuclear warhead being detonated underwater.

The weapon in question has an explosive power the equivalent of nine kilotons of TNT, or 9,000 tons.

It was positioned 500ft below the surface of the water, before being detonated and showing off its terrifying destructive power.

And if you are frightened by the power which this bomb shows off, then wait until you hear how it compares to other warheads.

That's because this bomb being tested here was actually a relatively small warhead, smaller than the bomb dropped on Hiroshima.

But if you think that's because people were getting worse at building nukes, think again as the small size was actually entirely deliberate.

There are two broad categories of nuclear weapons in terms of their size.

Shortly before the explosion. (Atomic Tests Channel)

The first category is the strategic nuclear weapon.

These are the very large, civilisation-ending type which are designed to be aimed at infrastructure and at population centres as a deterrent.

An exchange involving this sort of weapon is going to see deaths in at least the hundreds of thousands, and probably in the millions.

Weapons such as this are less a weapon so much as a diplomatic bargaining tool.

Then we come to the second type of weapon, which is what is being shown here.

This is the tactical nuclear weapon - a smaller warhead which is designed to be deployed in a relatively confined military setting.

On one occasion the US even experimented with a tactical nuclear weapon that could be fired from an artillery piece.

But what about the weapon being shown here?

Even the small explosion had enormous power. (Atomic Tests Channel)

The Mark 7 was designed to be dropped by a small fighter-bomber aircraft. This was an alternative to the larger strategic bombers which carried the larger weapons, until they in turn were superseded by the Inter-Continental Ballistic Missiles, or ICBMs, and nuclear submarines.

As for the test itself, this was the Wahoo Test, and was intended to study the effects of nuclear weapons in a naval setting.

And as you might imagine the results were devastating, with tons of water being hurled into the air by the force of the explosion and a test ship anchored some 2,346 feet away sustaining severe damage from the explosion.

The most powerful nuclear weapon developed by the US was the B-41, with a yield of 25 megatons.

Warheads themselves may now be smaller but that's small consolation due to a newer technology which allows for one missile to carry multiple warheads.

These are carried on the Trident submarines and can be used to either hit multiple targets with one missile, or to saturate an area with multiple hits.