Submarines

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On or near the surface, submariners 'see' through a periscope mast raised through the fin above the hull from within the submarine's Control Room. In the very latest submarines, the extendable periscopes will be largely superseded by an electronic mast that uses a camera and displays the picture on a monitor. The optronics masts have a closed circuit television (CCTV) camera to use by day or a thermal imaging (heat seeking) camera for use at night or in bad visibility.

Submarines cannot see underwater and so use sound energy to detect obstacles and objects. When under the water the submarine can emit SONAR (SOund Navigation and Ranging) sound waves through the water (know as 'pinging'). The sound wave or sonar ping echo is bounced back to the submarine if it detects another vessel or obstacle.

The strength of the returned signal or sound provides an indication of the range (distance) between the submarine and the other vessel (ship or submarine) or obstacle.

Modern submarines have excellent radio and satellite reception and communications systems and underwater telephones. When sending out sound waves by sonar, a submarine could be detected by another ship or submarine. When wishing to remain undetected, a submarine will listen for and hear sounds underwater through hydrophones (underwater microphones).

They had no weapons.

Nobody. The submarine was captured before it was sunk.

It didn't; Submarine Sonar wasn't developed until the '30's, and during WWII it saw limited use aboard submarines. Back then, it was essentially a bearing / speed indicator for a target, but not much more.

If the pressure of the water is greater than the air pressure inside the cabin, the walls will crack, the doors will open, water will pour in and the submarine will sink to the bottom of the sea/lake, flooded. ("walls and "doors" are improper words, bear that in mind).

their floating at a depth

Periscope.

Periscope, most modern subs ( WW-2 to date) have two, it is known now that submarines used by the Royal Italian Navy had an auxiliary zenith oriented periscopic theodolite/sextant that could be used to take fixes on celestial objects while at scope or siphon depth- also useful in tracking hostile aircraft- this aimed straight up, and was used mainly on Italian subs. Device was evolved by the Officine Gallileo or Gallileo Office- in Italian Officina is more like workshop or craft-assembly a small unit ( but high quality) shop- not a big mass-production factory. Of course on the surface sub officers and lookouts keep the watch with- Binoculars and these days some specialized night vision scopes...

Virginia class submarine

It doesn't require oxygen to operate. That means there is no smoke exhaust and no need to surface to power electrical batteries. They can stay under water as long as their is food for the crew.

Most submarines have propellers that spin, pushing them forward. A few smaller research submarines use a water jet for propulsion.

in excess of 400 feet

There is no set range limit for a periscope; it's affected by many factors, weather conditions playing a large part.

In addition to weather, the height of the periscope above the water, sea state (height of the waves), target profile (large, small, low or high in the water), daytime or nighttime, all affect a periscope's actual range.

A German submarine used in WW I was called a U-boat.

It doesn't need fins to move forwards, but fins are used to control rolling from side to side

Before the war, people mainly used ships and boats, therefore, the people with the submarine could destroy these ships.

Contrary to popular belief, women have been riding on board submarines (as tech riders, Midshipmen, etc.) for many decades; however, it's only recently that the Navy was directed to include billets for women to serve aboard U.S. submarines, a decision that's arguably as controversial as DADT.

Unlike the general Navy population, submarines duty is strictly volunteer; the biggest obstacle to inclusion of serving women onboard submarines has been crew wives, and the problem with an absolute lack of any privacy. The divorce rate among submarine crews is statistically higher than the rest of the Navy (about 75% when I was in), and such a forced decision won't make it any better.

There are also real health concerns (not necessarily radiological) that aren't publicized due to their classified nature, which is one reason submarine duty is volunteer and considered hazardous duty. Few of my crewmates ever got away free from submarine duty without some type of health issue - in my case, more than one. It's easy to be excited to volunteer for something when you don't know the long term risks, and the health risks for women are higher, something that hasn't been publicized.

For now, the plan is to only allow female officers aboard boats, since officer quarters are private anyway.

The 'helmsman' steers a submarine.

u boat

2 stored in Submarine Storage facility in Chittagong. They are currently under repair.

The existence of submarines forced other countries to develop anti-submarine weapons and detection systems.