Wonderful article. Reminds me of my experience scuba diving in Croatia. My group and I were doing a seabed waste-collection dive, and part of it was an obligatory training on ordnance. The sea there has had a fair few wars and conflicts.
I remember being astounded by how the water "amplifies" the explosions - so while a hand grenade blast is very dangerous on the surface, under the sea it becomes far more horrific prospect, due to the water transferring the blast more efficiently. Nerve wracking stuff, when you're thinking about diving down there - imagining that a bomb dozens of meters away could pulverize you.
Still pretty rare, thankfully. I applaud the diver bomb disposal squads - some of the most dangerous work there is.