I went on a retired submarine docked in the water at a Naval Base in Groton, Connecticut - no charge and it is a great experience, you walk down into the sub and walk from front to back - i highly recommend it if you are ever in that area!

To think of all the knowledge we've acquired since the first primitive rafts many thousands of years ago, it's staggering. Even just in the past hundred years, we've advanced by leaps and bounds.

As an honorably discharged US MARINE 1978 to 1987. I was on the LPD-9 the USS Denver, commissioned October 1968. The LPD is not that recent of an addition to the US Navy

Actually the first combat submarines date back to the American Revolutionary War. With the Turtle famously being the first used to attack another ship. (it failed). WW1 saw the first widespread and effective use of true ocean going submarines as weapons.

That was the Humlee ( I think that's correct) and was powered by hand cranking from its interior and could only sink to water level but could not dive. It leaked some too. It has been salvaged And is now a museum piece.

The hull number of the boat is painted in white letters on the conning tower when in US waters. When it ventures into "other" waters the letters will be painted out.

A lot of people get obssesed by giant sea creatures; giant squid, giant whale, giant shark etc. but I think a giant submarine is the most terrifying of them all.