Hi, I'm a lifter but I'm also first and foremost a long-distance freestyle/front crawl swimmer, so I may have a little bit to add. One-arm cable pull-downs are my new favorite dry-land "swim" exercise. I know of no better movement that mimics the single arm of a stroke, and it's also probably the best exercise there is for learning what lat utilization is. On land you can engage spinal flexion too (something you probably shouldn't do in the pool, given that you're trying to maintain streamline), which will further strengthen your lats.

Other exercices I've found helpful are the dumbbell pull-over (for similar reasons) and, strangely enough, the two-armed land-mine press. You wouldn't think that a press exercise would have much carryover for swimming (and especially not a two-handed one), but IMHO it's basically a stroke recovery (in other words, the motion your arm does AFTER it's completed it's stroke and is "recovering" into position the the next stroke) with resistance. I'm a distance swimmer, and I've found that form has been easier for me to maintain since I started incorporating this into my routine.