The Soviet/Russian SPP-1 underwater pistol was relatively unknown until the 1990s along with the rival German HK P-11 underwater psitol. The Soviet design arrived in 1971 a year after the W German weapon in 1970. The SPP-1 fires from a 4-barrel, 2 lb weapon with a rear loading cartridge. The rounds are 4.5x39mm darts, electrically fired. Each trigger pulls fires 1 round in sequence until the cartridge is empty and manually removed. AFAIK, it can be reloaded underwater. Meant to kill enemy divers, the range varied by depth from 6-18m. On land up to 20m. The rival HK P-11 is a 5-barrel weapon that fires 7.62x36mm darts but from a completely sealed frontal unit. After all the rounds are gone the entire unit is removed to be replaced completely. This cannot be done underwater, nor on land by the diver- it must be sent back to the factory for reloading. Not content to just have an underwater pistol the Soviets came up with an underwater AK!!!

SPP-1 pistol: http://www.cruffler.com/Features/NOV-01/4.5mmUnderwater.jpg Underwater AK: http://world.guns.ru/userfiles/images/assault/as69/aps.jpg HK P-11: http://world.guns.ru/userfiles/images/handguns/germany/hg209/1287726817.jpg