I played Civ4 for months when it first came out, and am playing it again...

I just realized, subs can move under ice caps! (sea squares with ice)

It's cool to discover totally new things :)

I was pumped to learn this too, it's real handy way of repairing them safely.

I was pumped to learn this too, it's real handy way of repairing them safely.

Provided the enemy doesn't send his own sub after you.

Useless until they fix the poles to work the way they do in real life.

Not totally useless. Sometimes there are small seas that go up to the ice caps but otherwise do not communicate with the oceans. You can get your subs there and destroy an enemy's fishing nets.

Plus, as The Lance mentioned, polar caps are the safest environment for your subs to repair.

Two more situations I hadn't thought of - repair, plus sub wars!

I have yet another situation that's actually where I discovered about the sub's mobility under ice - there was a %#@$$ barbarian galley on the Earth map in NW Canada that was trapped in a little strip of ocean surrounded by ice. Every single turn, it would move and I'd get a message about enemies near me. So I made a sub at a poor little town in the tundra up that way, and took him out. Just for the annoyance factor. That's when I found that the sub could get out of there anyway (and posted this thread).

Or more precisely, I could have sent a sub into there a hundred turns before and taken out that pest, lol.

I was pretty surprised when a sub I had automated ended up in a small body of water that wasn't accessible. Once I noticed this I discovered that the sub travelled there under the ice. I was pretty pleased to learn this little tidbit myself.

Useless until they fix the poles to work the way they do in real life.

Actually, I've used subs under ice caps to nice effect before, but it only works if your enemy doesn't also have subs. Because of subs high withdrawal chance, and if you can get them out of the factory with two promotions (drydock plus theocracy, for example) you can have a brand new sub with 80% chance of withdrawing from a battle. Have them sit under the ice and pop out to attack passing destroyers and battleships, upon withdrawing, dive back under the ice out of reach. then your own destroyers and battleships can come along and sink the wounded enemy ship in the next turn or so with minimal damage. It works a treat (as long as your enemy doesn't also have subs!)

Wow! I did not know they could do this! Next stop, Ice Station Zebra...

I've used this when the enemy has a port near a pole. Attack a ship, retreat and heal.

Useless until they fix the poles to work the way they do in real life.

Not useless if your enemy has to bring his/her ships through an Arctic pass in order to get to you. Subs make great sentries, and being under the ice like that they can't be attacked by anything but another sub. I once was able to take out an entire fleet because my sub gave me a warning that there were ships on the way. I just moved my fleet out in order to intercept them. They didn't even come close to landing on my shores, and the civ asked for peace shortly after.

The key in the value of subs under ice caps is your enemies not having subs. When they do have subs, you have to change tactics, though you can still do the same thing by having subs travel with a stack of destroyers and battleships. :) Rush out, attack with the sub and wound an enemy, withdraw, run back to the stack, then have the other ships finish the enemy for no loss.

what ice caps?

These are tiles that say "Ice/Ocean" or "Ice/Coast", as opposed to simply "Ice" (which is land).

It appears on most maps, at the upper and lower edges (North pole and South pole). But probably not every map.