I did a search on the word "submarine" on the website of Squadron Mail Order, one of the biggest and most popular online hobby product sources. Here's what I got: http://www.squadron.com/SearchResults.asp?ManuList=everything&Key=Submarine&ScaleList=everything&TypeList=everything&offset=0
The sheer number of products is kind of overwhelming - and how some of them made it onto that list is a little mysterious. They're in alphabetical order by manufacturer. Take a particularly close look at the kits listed under Trumpeter and Zvezda. The biggest assortment of modern subs is the line offered by Yankee Modelworks. These are resin kits - somewhat more challenging and considerably more expensive than styrene ones.
For an authoritative rundown on what's available, check out the kit review section of the Steel Navy website: www.steelnavy.com. That site also has links to a number of other distributors and kit manufacturers.
Hope that helps a little. I suspect some other Forum members will jump in with suggestions regarding specific kits.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.