Heck, there's Google (https://www.google.com/maps/views/streetview/oceans?gl=us&hl...), Virgin Oceanic (http://www.virginoceanic.com/), etc. exploring down there. Nothing wrong with a little deep sea action- even the military contribute.

It's much cheaper to explore the ocean than it is to explore space, and many benefits like: OTEC (http://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion http://cleantechnica.com/2013/05/05/lockheed-martin-to-build...), mining ( http://en.wikipedia.org/wiki/Deep_sea_mining), etc.

Others agree:

http://www.forbes.com/sites/quora/2013/01/31/why-dont-we-spe...

http://www.cnn.com/2012/04/09/opinion/etzioni-space-oceans/i...

But, I personally think we should be exploring space and our oceans. We need to make it a top priority of all countries to fund energy and propulsion research to help make exploration cheaper. That means allocating adequate budget and raising taxes for something that the mass media and our government doesn't seem to give much of a shit about, because they don't understand the part of the world we currently are utilizing is running out of resources quickly and that we are constantly a stone's throw from mass extinction.

You don't need Pu238 for deep sea exploration.

I wouldn't rule that out. Why wouldn't it make a great undersea battery?

Also, if we found Apollo 13 we could recover some Pu238:

http://science.slashdot.org/story/11/11/28/1637231/will-nasa...

http://unexplainedthings.tumblr.com/post/13563685365/will-na...

It would, but you don't need it because you don't need years or decades of power at high depths.

Espionage is not exploration, no matter what your congressman tells you.

The plutonium is for RTGs on benthic listening buoys, which are moored deep in the water column, or anchored directly to the sea floor. They have very sensitive hydrophones, and powerful burst ELF transmitters. This allows triangulation of targets.

They're made of steel and are never intended to be recovered - so we can look forward to plutonium salts in the oceans.

If I'm not mistaken the casing of it is very, very hard (even for space missions, where it's designed to whithstand a failed launch and reentry) and takes a very long time to degrade

Saltwater, astounding pressure and marine organisms make for a far harsher environment than the vacuum of space, or even a botched re-entry.

That said the argument I heard was that by the time they fall apart, the Pu has all but decayed.

The argument you heard is correct. The casings are likely made of something that is completely unaffected by saltwater, the pressures involved are neither astounding nor even interesting in this context, and... marine organisms? Which ones? Harsher than a botched re-entry?

The casings are steel, the rtg is in a ceramic capsule. You'd be amazed at what barnacles and such can pry wide open given time.

Wow you must be some kind of terrorist to even suggest such a thing.

Useless comment, fade away.