Thanks doc for bringing this sort of extreme environment to our attention, while some amongst us may find this sort of conditions a challenge to be beaten I feel that we should remind ourselves of a few basic safety practices.
1. Never enter without a buddy and at least a tenner in your pocket.
2. Lay a line, start by tieing off well outside to a fixed point ( lamp posts or bus stops are ideal )
3.Take a primary supply of sandwiches a secondary pork pie and a back up mars bar
4. Let someone know where your going and when you should return, a note to your mum should be adequate
5. There is a real danger of becoming disoriented - which could explain a lot about Jack
safe diving !!