And wschód - sunrise/east , zachód sunset/west.
It is very easy to navigate in Polish using sun :).
Could "Today we sail north" also be accepted? I'm sure both should should be, unless there's something that changes the meaning in polish?
Yes. Płyniemy is not only swim but all means of transport on water/in like ships, boats, ferry,
I am not English native speakers and I do not understand this sentence. What is its meaning?
I believe that using "sailing" could be more clear here. Today we are heading north, probably by boat (although theoretically we could be swimming, if we are great swimmers).
FWIW, I think the best translation here is "Today we are sailing North". It would be very, very unusual to say one swims north.