It's an original caption from a propaganda magazine. What would one expect? accuracy? And anything would sink in that mud/marsh, T34's were not designed to float... I mean they were less prone to sink that some german tanks. They had wider tracks, in order to decreese ground pressure. I remember reading a hungarian article about the combats in Hungary (surprise!), saying that where KT's, Tigers, narrow track Mark 4's sank, "oskettened" Mk. 4's and T-34's were still able to move. The terrain in Hungary was as bad, or in some cases even worse than in Russia when it came to mud (so Germans tried to stick to hardball).