The repeated comment by the individual Soldiers is how burdened they were with extra equipment, arms, explosives, and ammo to the extent they were unable to move with any speed or agility much less swim.
As a fit and professional military man in my youth I took part in a landing craft assault. These were the old WWII craft with the crash down doors at the front. All I had was an SLR (an M4 size rifle), a small backpack and webbing belt with water bottle etc. We were dropped for draught considerations up to our neck in water. By the time I got to the shore I was absolutely done in and all I could do was lay there trying to get my breath, as were all of my colleagues.
I have no idea at all how young conscripts, weighed down with up to a hundred pounds of kit, tin helmet et al got off the beach at all. They were amazing men, but then I suppose they were amazing times.