You know, I never really figured out why did people need to put seeker heads on their gyrojet rounds. You have one skill to lock on, another to shoot the damned weapon. I can understand if one guy has a designator and the other has the gun but...

I would recommend a gunlight on the gyrojet pistol.

Um, I'm not really seeing how having extendable legs would make you swim faster. :/

It would if they had giant flaps put on the end of them!

I could claim easily that high-temp tolerance requires something to eliminate heat, and is therefore impossible.

The main mechanism for eliminating heat in humans is sweating, thus you need to constantly put in "water" every time you go empty on sweating materials.

Actually heat is a physiologically harder problem for a large animal like a human, very hot environments are notable for their lack of large endothermic animals (camels don't live in the hottest deserts, they can just cross stretches of them, and they are pretty much top of the line), while in very cold ones large endothermic animals are very sucessfull (polar bears, reindeer, whales, seals, emperor penguins, etc live thier whole lives in the coldest parts of the world). Brown fat can more efficiently convert food to heat than some of the mechanisms adult humans use (eg shivering), and even adult humans have a small amount of brown fat (infants, bears, and squirrels have a lot more). In addition large parts of the body can be allowed to drop well below normal core temperature as long as they don't freeze without permenant damage, birds are very good about that. Some mammals can drop thier body temperatures by many degrees, remain somewhat active then raise it back up rapidly when necessary. The strategy in hot environments is to simply be inactive or to seek microclimates to avoid the heat (such as burrows). Humans are already one of the more heat tolerant large animals so we would also be more difficult to further optimize in that direction.

Increased food intake in the cold would be a good side effect though.

Absorbing heat could raise it up, both are pretty much themodynamic nonsense though. Any cold environment is going to be colder than our bodies, any hot one hotter than our bodies. You can get a bit of benefit from things like that when in a cold, but sunny environment, or if you were overheating due to excercise in a relatively cool environment. Our bodies already radiate whatever heat they can when overheated, and there isn't much you can do to a hairless animal with pretty large surface area to volume to make it radiate more. SOTA 2063 talks about increasing blood flow to the skin, but really we already do that, thats why one gets flushed when hot. Similarly we reduce blood flow to the skin when cold.

Heh, the best part is that low temperature tolerance is in sota 2063, I just didn't remember it.

I don't see a laser designator as your best option. The deeper you go underwater, you lose some of the color spectrum. Maybe your guy won't go that deep though, or maybe it wouldn't affect functionality.

Red is the last color you'd want though, as it is one of the first in the spectrum to be absorbed. I was diving in Hawaii with a buddy who cut his hand and bled green.

I made sure to check if his ears were pointy when we got back up!

dunno, but it seems to me that they must have something planned for it, considering that's gotta be a large part of the market for the weapon.

Actually there's a product on the market that rapidly lowers the body's temperature by circulating cold water through a glove. The body's heat-exchange is far from optimally designed, and I'd think there would be a lot of little things you could do to improve it.

Things get more interesting when the ambient temperature is higher than the body's, I agree, but provided you had an insulated reserve of some heat absorbing substance you could still probably cool yourself in the short term.

Not that difficult. Point the end with the hole in it at the other other guy and keep pulling the trigger until it stops going bang and then reload pretty much sums it up for me.