First of all I've searched using the search bar and found nothing useful on this subject so I thought I'd ask :)

Well my question is, would it be possible to add actual swimming mechanics in CoD4 through scripting? Such as making you sink gradually and making space bar make you swim upwards.

Also, I'd guess there are no swimming animations stock in the CoD4 files so would it be possible to create them myself and add them into the game?

Ps. Are there any current mods that have been released that feature this that I could take a look at? (Although I do want to be able to create a mod myself, to increase my knowlege of scripting)

Thanks for any responses :)

You can try to look on codwaw, it had something close to swimming I think. So you can check the scripts (not sure if treyarch gave these) and the animations.