I agree with cowboy, it's still very young. You could use this heat to your advantage with the love of water. Just take the pup out playing near some shallow water. When the pups good and hot from running around. Throw something in the water near shore to lure the pup in. The cooling effect of the water should do the rest. No pressure from you at all. Just let the pup explore this on it's own. Running around with a trusted older dog could also help if the pup is timid.
Have fun!