Verified answer

Yep. I saw him swim in the leaked GTA IV videos that were circulating the web. You'll find some more gameplay if you watch IGN's review on their site.

None of the leaked footage or any video reviews have include any water action in the game probably because its normally the most boring form of transport but if niko on a next console can't and cj from sam andreas could i personally think that would be pretty messed up, its more than likely he will swim especially with the game being island based if you were to take a boat and couldt swim would that be pointless. Happy gaming!

I would assume so. It would be pretty hard to use boats otherwise. If you can't swim you might as well not put boats in the game at all.

I know in San Andreas I always had to ditch the boat I was using since helicopters and other boats made it into swiss cheese (I could usually manage to steal another). It would be pretty ridiculous if swimming was removed.

I think it's a must for a next-gen game. Even CJ from GTA SA could swim, so, imho, Niko would be able to do it.

If they've overhauled everything this much, I would doubt they'll take it out. I hope they don't because that used to always add an extra level of hardness in certain missions. I mean, come on Rockstar, who drownds in 2 feet of water.

No...He's a white guy...

Only Black people can swim in the GTA universe...

Yes he can according to this

no u will drown in water

no