Hello.

Last night I saw a show about the A.E.2.
The A.E.2 was an Australian Sub that was in Gallipoli and helped the Anzacs land by scaring off a ship that was 12k's away from the landing site had been shelling them.(now, I know 12k's sounds like along way from the landing site for a ship to shell but the thing is that ship had enough fire power to do that.)

The A.E.2 was the only Sub to go almost around the world of the time.
It had a very smart crew and Captain, at one point the Sub had been seen by the enemy and had to go down, and after that there was all these different ships searching for them, the crew also had to stay as still as they could, there was also a ship that was looking for them(in those days there wasn't sonar so they had to use a grappling-hook) with a grappling-hook that the enemy would have sent bombs down if it were to catch on something, but it only scraped along the hull of the Sub, but luckily didn't catch on the hull.

If you want to know more about the A.E.2 then click here.