(bolding done by me for emphasis)
"Someone tell me why we aren't having the field agents investigate this." Dr.Brown demanded.
There should be a space between "Dr." and "Brown." This problem comes up more than once, so I'll only explain it here.
"…they have no clue what to look for," Her British tone was scornful.
As stated by VAE, "tone" should probably be "accent." "Her" should be "her," and this is just a peeve of mine, but British accents aren't all the same. Technically, a Scottish accent is British, as is a Welsh accent, but neither of those sound the same as an Irish or English accent.
Downright cold, but it should have been expected coming down to the arctic. "Look everything's going to be fine John. We take this hunk a junk down there."
I think "arctic" should be "Arctic.;" that there should be commas between "Look" and "everything's," and "fine" and "John;" and that "a" should be "of." The last one is purely stylistic, though. I'd also have worded it "going up to the Arctic," but again, that's stylist choice.
"Whats the worst that can happen?"
*What's
"Alright, but you're to tell me that right now, this very second you aren't nervous?"
I'd put a comma there.
The Intercom screeched
I don't think "Intercom" deserves a capital letter.
"Iceberg is strait ahead."
I think you meant "straight"
"A European fishing vessel came across it and were as perplexed as us to find that it wasn't on the map."
Europe is an entire continent. It'd be easier to just say "local," but you can also name a country that is technically part of Europe, like Iceland.
"Come on in Sarah it's cozy in here…like a prison cell with buttons."
I'd put a comma between "in" and "Sarah," and a period between "Sarah" and "it's."
"Well we got news of an earthquake originating from this exact location."
Comma
In fact it might have gotten even more frigid.
Comma
"Look at that, frost is forming on the glass."
I'd put a period instead of a comma.
"…temperature just dropped past minus 17"…"
I do believe you meant "17°." The word "degrees" would also work.
The bottom was no where in sight…
"Nowhere" would also be grammatically correct, I think.
"It's a bloody mountain. sticking right out of the side of this thing. Hey get a sample of it would you?"
I'd say commas between both sections of bolded words. I'd also say that there should be a longer pause between the two sentences.
Dr.Brown stopped panning past it and used the robotic arms to collect a piece.
I'm not sure if panning is the correct word to use, but if you go with my "replace sub with a robot" suggestion, it'll be fine. I also think the second half of the sentence should be reworded because it implies that they got the sample, but the next sentence explicitly says the thing started moving before they could.
Cold sweat grasped at the two in the submersible
This sentence needs a period.
In one brief motion the light swept open to reveal an eye.
I'm not sure what's happening here. What light, and how is it sweeping open? Please reword this to clarify.
Next it blinked.
I'd have said, "And then it blinked." That's stylistic, though.
Each of them were white with terror and frozen in place.
I'd put "Both Sarah and (Dr. Brown's first name here)" instead. Also, I see no references to Brown's first name. It might be a good idea to expand his and the captain's character a bit, but again, that's personal style.
"I repeat inform the 05 possible XK class event."
Even in emergencies, people what use radios (like the Foundation and militaries) try to use complete sentences. I know. I'm a volunteer firefighter.