the star trek early-20th-century antarctic exploration AU (AU both of Star Trek, and of real life because women were unfortunately not allowed on an expedition before the mid-century) I will never write, but really want to: 

it’s a privately-funded American expedition (Pike helps fundraise? idk) Kirk is the expedition’s charismatic leader, with Spock as the chief scientist (geophysicist studying the earth’s magnetic field, with an additional degree in geology) and second-in-command. Chekov is a russian ski expert and is also, along with Sulu (who is also a botanist), in charge of the sled-dogs. Scotty is the engineer, and, off the ship, is in charge of making the new-fangled motorized sledges work. Uhura is the radio operator and in charge of getting the equally new-fangled radio tower up and running. McCoy is a medical doctor as well as a biologist, and Chapel is both biologist and medic. 

mostly this whole thing is a set-up for Kirk leaping off the ship and onto the ice, spreading his arms, and saying “Antarctica! The final frontier!” Also, Chekov trying to teach the rest of them to ski and then laughing at the attempts, Sulu’s first experience with snow (california boy!), Chapel trying to catch penguins for study, McCoy ranting about scurvy and demanding everyone eats more sauerkraut, Uhura chatting with the relay station in morse code about how bonkers they all are during the long (LONG) winter, Spock trying (and failing) to manage a rowdy team of dogs, Scotty playing the bagpipes to an indifferent penguin swearing at machinery not designed for extreme cold.