Buildings and Infantry.

[DRG]

To make ones that change radically when they are in and out of the water yes. You will notice that the DD uses one Icon for summer, winter or desert on land and both Tauch use different icons for summer, winter and desert but still produce the snorkel graphic in the water


That said, all it takes to make something swim is to give it a swim speed but the DD and the Snorkel tanks were special cases