Regarding the gold bar "feature", I'd just remove it. Game studios drop months of story lines if they don't fit, no shame in that and only makes the game better.
My two cents: realistically if a person grabs heavy loot, they can just drop it, pick it up later, use your arms to "climb out" instead of swimming, and the gold bar doesn't weigh as much in the water. So there is no way a gold bar would insta-kill me. Plus I'd only read the objectives when I'm in a safe spot outside, keeping all objectives in-mind while digging in dark murky water is not the place for a player, especially in panic.
Awesome atmosphere otherwise!