I took Zeus and Ben down to the river today. Ben jumped straight in without being told he could today. Normally, he'd wait for a command, but it seems he couldn't contain his excitement and launched himself, paws outstretched, into the deeper part of the river. Little Zeus got excited by the water too, but wouldn't dare venture further than the safety of the small cove despite Ben showing him the way (Zeus will only go in upto his neck thus far). Nevertheless, upon climbing back on to the river bank Zeus was playing around with another dog when he lost his footing and fell into the river in a deeper area. He couldn't climb back up and so had to swim back to the cove - he wasn't impressed!
Despite my best efforts to get him to swim he won't do it voluntarily so far. Time will tell if he plucks up enough courage to follow Ben's lead (no pun intended).