I personally did not lose a whole crate. A few times with a certain set of crew some product was left on the beach uncrated and caught in the incoming tide. Keeping pace with the tides was a big part of the job so it was mostly a rookie mistake.

A few times some crates spilled or flipped on the lift and haul up onto the barge when you were chest deep and lifting over your head, but I only ever lost maybe a dozen in the six years I did it. A full crate actually sinks at a fairly slow rate so if you lose your grip you can just let it drop and scoop any floaters trying to escape.

Now I did have to dive couple feet a few times for a sinking crate but nothing far out of reach of my headlamp. Definitely spooky though.