Dangerous Waters is a very serious naval warfare simulator with a primary focus on submarines, although other platforms are also controllable, such as the MH-60R and the Oliver Hazard Perry. The game's complexity arises not from navigating within your submarine or from having to press a million buttons -- indeed, these mechanics don't even exist. Instead, the game's interface is surprisingly simple for the most part as you move instantly from one screen to the next, and the graphics are rather bland, even on the highest settings, which is a bit understandable considering the game came out about a decade ago (as of this review year). Instead, the difficulties for the new player will be conceptual, and the learning curve for that will probably feel rather high at first.
For those who master the basic concepts behind Dangerous Waters, this game largely tests your ability to be a decent submarine captain. The primary concepts to master in this game are probably those that have to do with sonar. Once a player knows how to utilize his sonar station, he is in a very good position to begin serious consideration of tactics.
At this point, the player should see Dangerous Waters open up into a very serious cat-and-mouse game of war in which the superior tactician can often seize an advantage. Imagine a scenario in which a a submarine captain notices that he's stumbled onto an enemy submarine. Through Narrowband sonar, he determines that the submarine is a Russian Kilo. The captain knows that the Kilo doesn't have a towed sonar array, making it deaf to anything directly behind it. Accordingly, the captain orders a course change and swings in behind the Kilo. This Kilo's hunt for surface ships will be over soon.
Nothing quite matches the anticipation of watching one's own torpedoes travel at the enemy, or the anxiety caused by listening to the constant pinging of enemy torpedoes as they get closer and closer while actively searching for their target. For those who can put up with the game's graphical shortcomings and high learning curve, this game is definitely an awesome submarine simulator.
CAVEAT: This game does NOT run natively on Windows 8. It will, however, run in a virtual machine. It also reportedly works through WINE on Linux.