Explosive charges are frequently heard for miles underwater in parts of the Philippine Islands where types of destructive "dynamite" or "blast" fishing methods are employed. Any diver anywhere near (within about a mile) of the explosion may think their dive buddy's scuba tank exploded, since the concussion and sound is so intense. If the explosion is very close, the diver's eardrums will rupture, as once happened to two members of our dive club. After the explosion, some fish float to the surface, and others sink to the bottom. The fishermen then collect the floating fish, and sometimes don a mask and flippers to collect the fish that sink.
As with other destructive fishing techniques, the habitat for the fish is destroyed, preventing them from breeding. The end result is an unhealthy, devastated reef with many fewer fish for future catches. A cycle is created, with increasingly desperate fishermen willing to resort to any method to catch some of the dwindling fish-- methods that only yield short-term gains in return for much larger long-term losses.
This one liter Coca-Cola bottle, found near one of the Capone islands, still shows a slightly burned fuse and explosive sediment inside. I was wondering how unstable the charge was at about the time my strobe discharged as I was taking this shot... needless to say I didn't disturb the bottle afterwards.