I used to work at hse, been down most of the tunnels, never saw any weapons of mass destruction. There was one bit we weren't allowed to go as it had old mustard gas cannisters in it which were deemed unstable, I guess someone disturbed them.
We regularly had bomb disposal up there as someone was always finding ammunition in the ground, they also used it for training, came up, spent a few days metal detecting then end of week blowing their finds up in one of the bunds.
As for the blue lagoon, we used to go swimming there from collage, some mates pushed their car off the cliff into it and you sometimes saw a dead sheep in it likely killed from the fall.
The 'autorities' were always crying its a death trap but I personally don't remember anyone dieing in it although do remember someone being airlifted to hospital from it once because they jumped in and got impailed on somthing in the water.
Nice to see it again.