Enlisting in the navy - your experiences?

[Ula Jolly]

I am thinking about enlisting in the navy next year. Having played around quite a bit with Dangerous Waters and sims of the like, and having an interest in (but hardly the head for) maths, I thought sonar room service was one of the things I wanted to try to acheive.
Now, I'm sure the US/UK/any navy will differ from another, but the country in question is Norway. I can't imagine the inter-NATO differences are extreme when it comes to boating, and I'd basically just love to hear your personal experiences with service in the navy, aboard a boat.
Questions arise such as, what requirements should I prepare for? Physically as well as regarding mathematics. It's all processed on a screen nowadays, but what should I prep for, if anything? Also I guess sonar duty would require a pretty damned keen ear above anything else, so that's halfway not up to me. Can I amaze them with my hobby gaming* enthusiasm?

*the unspoken word, perhaps?