I could pretty much name the order that everyone was going to die from the start

romance between the two young attractive co-stars who go into the mission with a significant other

Okay, basic plot: The outer core of the earth has stopped spinning for unknown reasons. This, naturally, has screwed with the "protective electromagnetic field of the earth". Not once were actual terms for such things as the Van Allen belt used, mind you. This is causing all sorts of hell on earth: as wacky EMP pulses which stop pacemakers and yet don't seem to interfere with the street lights, weird animal behavior such as pigeons getting fed up with going coo all day and attacking a London suburb, and eventually even a big giant microwave beam from the sun that melts a good chunk of the golden gate bridge and half the town of San Francisco.

In any case, ignoring the bad science, they decide they have to start the core spinning again. It's a big thing, so you need a big explosion to do it (of course...) Surprise, surprise, let's take a nuke down there and blow the hell out of it. What the hell, make it 5 nukes.

So they build a ship that not only can withstand the pressures involved due to it's hull made of "unobtainium" (I couldn't make this stuff up if I tried), they build it like a train, with 6 compartments to it. Mounted on the front is a big ultrasonic laser like device which makes rock magically disappear or something. In any case, they stick 6 guys in it including two college professors (one of which is in a seemingly unrelated field), two astronauts (one of which is the required "hot chick"), the designer of the ship (wacky guy in a desert working on this sort of thing for the last 20 years), and one annoying professor/science/government guy (who stole the designer's stuff 20 years ago and thus was the guy who put him in the desert in the first place). They somehow have video communication with the mission control all the way down, and somehow missed the fact that if they have that, they could have made the ship remote controlled and a third of the size. Oh, and let's not forget the uber-hacker guy named "Rat" they get to "control the internet" so that the whole thing can remain secret, but who ends up screwing the government over in order to help the crew of the ship.

Now, we've got these guys going to the core. Appearantly, this magic ship can do about 60 knots through solid ****ing rock, so they're making good time. Then they crash into a giant hollow ****ing geode just sitting around in the mantle. My BS indicator exploded when I saw this wacky nonsense. They're crashing through badly made fake purple crystals the size of a tractor trailer, and this of course jams their spinning laser dealie. So they have to get out to fix the damn thing, which requires using half of their liquid nitrogen cooling system to cool door off (poor design). Oh yeah, and they poked a hole in the top of the geode thing coming in, so it's now filling up with liquid hot magma.

So, there's some heroics, the commanding pilot dies, thus putting the hot girl in charge. They narrowly escape, get to the outer core, and realize that the bomb won't work because they screwed up the calculations. At this point it's revealed by the annoying government scientist that there's a backup plan called "Destini" that was the cause of the whole problem to being with. They stole this idea from somewhere, where exactly I forget. The idea is that of a big earthquake machine that, using electromagnetics, can cause an earthquake at any point on the globe. They messed it up and it's what stopped the core spinning. Plan B is to use it again to attempt to restart it. Naturally, this is damn risky, they all know it, and the remaining crew on the ship isn't having any. Rat, our annoying uber-hacker, hacks the thing and reroutes it's power to Coney Island to buy some more time.

So they come up with the wonderful idea that instead of one big 1000 megaton blast, they'll have 5 200 megatons blasts in series to get it spinning again (damn good thing that they didn't bring just one bomb). Oh, except that the nukes won't stand the pressure. Good thing we have 5 remaining ejectable compartments on the ship, huh? The designer has to die to make it possible to eject them (poor design again) but it'll work. At the last minute they realize that the last nuke has to be bigger than the rest for some reason, so the guy takes the fuel rods from the reactor powering this digging ship and tosses them in there with the nuke before ejecting it. Naturally, this leaves them dead in the magma.

But wait! With just minutes to spare, professor guy remembers that unobtainium generates energy when it's hot! So, with some incredibly fast rewiring, and even welding no less, they get the ship powered up, and ride the shockwave up to Hawaii. Of course, they come out underwater, where it's cold, and so lose power with only 800 feet to go. However, our uber-hacker, Rat, surmises that due to the ultrasonics, they can find them by, believe it or not, following the freakin' singing whales, and all is good.