The Royal New Zealand Air Force has a small fleet of these planes too! See them flying around all the time.
So does Australia, Japan and a few other countries. We're suppose to be phasing them out starting in 2015 with a 737, but like anything..I'll believe it when I see it.
I was shocked to learn how many aircraft stay in service for years and years... Til I reallized how much insurance/regulation costs to manufacturers have driven up the cost of new aircraft (of course I'm speaking more on a civillian level...)
Everything I touch on a regular basis (except for my significant other) are Japanese and over the age of 35 (76 Yamaha and Takamine guitars, a 72 Seiko, and my Z), and as long as none of those things ever touch water, they're fine
I'd imagine similarly for those planes.
Actually these planes see Saltwater on a regular basis! We have what's called a "birdbath" on the flightline, the planes or helicopters will taxi through it slowly to rinse off all the saltwater that is on the aircraft, if they were flying low over the water. Pretty much a carwash just for Propeller driven aircraft and Helicopters. The P-3 carries Torpedoes in its' bomb bay and has sonar bouy shoots on the belly.